diff --git a/src/vs/base/common/map.ts b/src/vs/base/common/map.ts
index 5d79ad368a744..611078e185220 100644
--- a/src/vs/base/common/map.ts
+++ b/src/vs/base/common/map.ts
@@ -580,7 +580,9 @@ export const enum Touch {
 	AsNew = 2
 }
 
-export class LinkedMap<K, V> {
+export class LinkedMap<K, V> implements Map<K, V>{
+
+	readonly [Symbol.toStringTag] = 'LinkedMap';
 
 	private _map: Map<K, Item<K, V>>;
 	private _head: Item<K, V> | undefined;
@@ -632,7 +634,7 @@ export class LinkedMap<K, V> {
 		return item.value;
 	}
 
-	set(key: K, value: V, touch: Touch = Touch.None): void {
+	set(key: K, value: V, touch: Touch = Touch.None): this {
 		let item = this._map.get(key);
 		if (item) {
 			item.value = value;
@@ -658,6 +660,7 @@ export class LinkedMap<K, V> {
 			this._map.set(key, item);
 			this._size++;
 		}
+		return this;
 	}
 
 	delete(key: K): boolean {
@@ -701,34 +704,13 @@ export class LinkedMap<K, V> {
 		}
 	}
 
-	values(): V[] {
-		const result: V[] = [];
-		let current = this._head;
-		while (current) {
-			result.push(current.value);
-			current = current.next;
-		}
-		return result;
-	}
-
-	keys(): K[] {
-		const result: K[] = [];
-		let current = this._head;
-		while (current) {
-			result.push(current.key);
-			current = current.next;
-		}
-		return result;
-	}
-
-	/* VS Code / Monaco editor runs on es5 which has no Symbol.iterator
 	keys(): IterableIterator<K> {
-		const current = this._head;
+		let current = this._head;
 		const iterator: IterableIterator<K> = {
 			[Symbol.iterator]() {
 				return iterator;
 			},
-			next():IteratorResult<K> {
+			next(): IteratorResult<K> {
 				if (current) {
 					const result = { value: current.key, done: false };
 					current = current.next;
@@ -742,12 +724,12 @@ export class LinkedMap<K, V> {
 	}
 
 	values(): IterableIterator<V> {
-		const current = this._head;
+		let current = this._head;
 		const iterator: IterableIterator<V> = {
 			[Symbol.iterator]() {
 				return iterator;
 			},
-			next():IteratorResult<V> {
+			next(): IteratorResult<V> {
 				if (current) {
 					const result = { value: current.value, done: false };
 					current = current.next;
@@ -759,7 +741,29 @@ export class LinkedMap<K, V> {
 		};
 		return iterator;
 	}
-	*/
+
+	entries(): IterableIterator<[K, V]> {
+		let current = this._head;
+		const iterator: IterableIterator<[K, V]> = {
+			[Symbol.iterator]() {
+				return iterator;
+			},
+			next(): IteratorResult<[K, V]> {
+				if (current) {
+					const result: IteratorResult<[K, V]> = { value: [current.key, current.value], done: false };
+					current = current.next;
+					return result;
+				} else {
+					return { value: undefined, done: true };
+				}
+			}
+		};
+		return iterator;
+	}
+
+	[Symbol.iterator](): IterableIterator<[K, V]> {
+		return this.entries();
+	}
 
 	protected trimOld(newSize: number) {
 		if (newSize >= this.size) {
@@ -961,9 +965,10 @@ export class LRUCache<K, V> extends LinkedMap<K, V> {
 		return super.get(key, Touch.None);
 	}
 
-	set(key: K, value: V): void {
+	set(key: K, value: V): this {
 		super.set(key, value, Touch.AsNew);
 		this.checkTrim();
+		return this;
 	}
 
 	private checkTrim() {
diff --git a/src/vs/base/test/common/map.test.ts b/src/vs/base/test/common/map.test.ts
index c9a99858854e2..d10d2176cb58d 100644
--- a/src/vs/base/test/common/map.test.ts
+++ b/src/vs/base/test/common/map.test.ts
@@ -13,8 +13,8 @@ suite('Map', () => {
 		let map = new LinkedMap<string, string>();
 		map.set('ak', 'av');
 		map.set('bk', 'bv');
-		assert.deepStrictEqual(map.keys(), ['ak', 'bk']);
-		assert.deepStrictEqual(map.values(), ['av', 'bv']);
+		assert.deepStrictEqual([...map.keys()], ['ak', 'bk']);
+		assert.deepStrictEqual([...map.values()], ['av', 'bv']);
 		assert.equal(map.first, 'av');
 		assert.equal(map.last, 'bv');
 	});
@@ -23,16 +23,16 @@ suite('Map', () => {
 		let map = new LinkedMap<string, string>();
 		map.set('ak', 'av');
 		map.set('ak', 'av', Touch.AsOld);
-		assert.deepStrictEqual(map.keys(), ['ak']);
-		assert.deepStrictEqual(map.values(), ['av']);
+		assert.deepStrictEqual([...map.keys()], ['ak']);
+		assert.deepStrictEqual([...map.values()], ['av']);
 	});
 
 	test('LinkedMap - Touch New one', () => {
 		let map = new LinkedMap<string, string>();
 		map.set('ak', 'av');
 		map.set('ak', 'av', Touch.AsNew);
-		assert.deepStrictEqual(map.keys(), ['ak']);
-		assert.deepStrictEqual(map.values(), ['av']);
+		assert.deepStrictEqual([...map.keys()], ['ak']);
+		assert.deepStrictEqual([...map.values()], ['av']);
 	});
 
 	test('LinkedMap - Touch Old two', () => {
@@ -40,8 +40,8 @@ suite('Map', () => {
 		map.set('ak', 'av');
 		map.set('bk', 'bv');
 		map.set('bk', 'bv', Touch.AsOld);
-		assert.deepStrictEqual(map.keys(), ['bk', 'ak']);
-		assert.deepStrictEqual(map.values(), ['bv', 'av']);
+		assert.deepStrictEqual([...map.keys()], ['bk', 'ak']);
+		assert.deepStrictEqual([...map.values()], ['bv', 'av']);
 	});
 
 	test('LinkedMap - Touch New two', () => {
@@ -49,8 +49,8 @@ suite('Map', () => {
 		map.set('ak', 'av');
 		map.set('bk', 'bv');
 		map.set('ak', 'av', Touch.AsNew);
-		assert.deepStrictEqual(map.keys(), ['bk', 'ak']);
-		assert.deepStrictEqual(map.values(), ['bv', 'av']);
+		assert.deepStrictEqual([...map.keys()], ['bk', 'ak']);
+		assert.deepStrictEqual([...map.values()], ['bv', 'av']);
 	});
 
 	test('LinkedMap - Touch Old from middle', () => {
@@ -59,8 +59,8 @@ suite('Map', () => {
 		map.set('bk', 'bv');
 		map.set('ck', 'cv');
 		map.set('bk', 'bv', Touch.AsOld);
-		assert.deepStrictEqual(map.keys(), ['bk', 'ak', 'ck']);
-		assert.deepStrictEqual(map.values(), ['bv', 'av', 'cv']);
+		assert.deepStrictEqual([...map.keys()], ['bk', 'ak', 'ck']);
+		assert.deepStrictEqual([...map.values()], ['bv', 'av', 'cv']);
 	});
 
 	test('LinkedMap - Touch New from middle', () => {
@@ -69,8 +69,8 @@ suite('Map', () => {
 		map.set('bk', 'bv');
 		map.set('ck', 'cv');
 		map.set('bk', 'bv', Touch.AsNew);
-		assert.deepStrictEqual(map.keys(), ['ak', 'ck', 'bk']);
-		assert.deepStrictEqual(map.values(), ['av', 'cv', 'bv']);
+		assert.deepStrictEqual([...map.keys()], ['ak', 'ck', 'bk']);
+		assert.deepStrictEqual([...map.values()], ['av', 'cv', 'bv']);
 	});
 
 	test('LinkedMap - basics', function () {
@@ -136,13 +136,15 @@ suite('Map', () => {
 		assert.strictEqual(cache.size, 5);
 		cache.set(6, 6);
 		assert.strictEqual(cache.size, 5);
-		assert.deepStrictEqual(cache.keys(), [2, 3, 4, 5, 6]);
+		assert.deepStrictEqual([...cache.keys()], [2, 3, 4, 5, 6]);
 		cache.set(7, 7);
 		assert.strictEqual(cache.size, 5);
-		assert.deepStrictEqual(cache.keys(), [3, 4, 5, 6, 7]);
+		assert.deepStrictEqual([...cache.keys()], [3, 4, 5, 6, 7]);
 		let values: number[] = [];
 		[3, 4, 5, 6, 7].forEach(key => values.push(cache.get(key)!));
 		assert.deepStrictEqual(values, [3, 4, 5, 6, 7]);
+
+		assert.deepEqual([...cache.entries()], [[3, 3], [4, 4], [5, 5], [6, 6], [7, 7]]);
 	});
 
 	test('LinkedMap - LRU Cache get', () => {
@@ -150,11 +152,11 @@ suite('Map', () => {
 
 		[1, 2, 3, 4, 5].forEach(value => cache.set(value, value));
 		assert.strictEqual(cache.size, 5);
-		assert.deepStrictEqual(cache.keys(), [1, 2, 3, 4, 5]);
+		assert.deepStrictEqual([...cache.keys()], [1, 2, 3, 4, 5]);
 		cache.get(3);
-		assert.deepStrictEqual(cache.keys(), [1, 2, 4, 5, 3]);
+		assert.deepStrictEqual([...cache.keys()], [1, 2, 4, 5, 3]);
 		cache.peek(4);
-		assert.deepStrictEqual(cache.keys(), [1, 2, 4, 5, 3]);
+		assert.deepStrictEqual([...cache.keys()], [1, 2, 4, 5, 3]);
 		let values: number[] = [];
 		[1, 2, 3, 4, 5].forEach(key => values.push(cache.get(key)!));
 		assert.deepStrictEqual(values, [1, 2, 3, 4, 5]);
@@ -169,7 +171,7 @@ suite('Map', () => {
 		assert.strictEqual(cache.size, 10);
 		cache.limit = 5;
 		assert.strictEqual(cache.size, 5);
-		assert.deepStrictEqual(cache.keys(), [6, 7, 8, 9, 10]);
+		assert.deepStrictEqual([...cache.keys()], [6, 7, 8, 9, 10]);
 		cache.limit = 20;
 		assert.strictEqual(cache.size, 5);
 		for (let i = 11; i <= 20; i++) {
@@ -181,7 +183,7 @@ suite('Map', () => {
 			values.push(cache.get(i)!);
 			assert.strictEqual(cache.get(i), i);
 		}
-		assert.deepStrictEqual(cache.values(), values);
+		assert.deepStrictEqual([...cache.values()], values);
 	});
 
 	test('LinkedMap - LRU Cache limit with ratio', () => {
@@ -193,11 +195,11 @@ suite('Map', () => {
 		assert.strictEqual(cache.size, 10);
 		cache.set(11, 11);
 		assert.strictEqual(cache.size, 5);
-		assert.deepStrictEqual(cache.keys(), [7, 8, 9, 10, 11]);
+		assert.deepStrictEqual([...cache.keys()], [7, 8, 9, 10, 11]);
 		let values: number[] = [];
-		cache.keys().forEach(key => values.push(cache.get(key)!));
+		[...cache.keys()].forEach(key => values.push(cache.get(key)!));
 		assert.deepStrictEqual(values, [7, 8, 9, 10, 11]);
-		assert.deepStrictEqual(cache.values(), values);
+		assert.deepStrictEqual([...cache.values()], values);
 	});
 
 	test('LinkedMap - toJSON / fromJSON', () => {
@@ -237,7 +239,7 @@ suite('Map', () => {
 		map.delete('1');
 		assert.equal(map.get('1'), undefined);
 		assert.equal(map.size, 0);
-		assert.equal(map.keys().length, 0);
+		assert.equal([...map.keys()].length, 0);
 	});
 
 	test('LinkedMap - delete Head', function () {
@@ -251,8 +253,8 @@ suite('Map', () => {
 		map.delete('1');
 		assert.equal(map.get('2'), 2);
 		assert.equal(map.size, 1);
-		assert.equal(map.keys().length, 1);
-		assert.equal(map.keys()[0], 2);
+		assert.equal([...map.keys()].length, 1);
+		assert.equal([...map.keys()][0], 2);
 	});
 
 	test('LinkedMap - delete Tail', function () {
@@ -266,8 +268,8 @@ suite('Map', () => {
 		map.delete('2');
 		assert.equal(map.get('1'), 1);
 		assert.equal(map.size, 1);
-		assert.equal(map.keys().length, 1);
-		assert.equal(map.keys()[0], 1);
+		assert.equal([...map.keys()].length, 1);
+		assert.equal([...map.keys()][0], 1);
 	});
 
 
diff --git a/src/vs/workbench/browser/parts/editor/editorsObserver.ts b/src/vs/workbench/browser/parts/editor/editorsObserver.ts
index 47d62dc935135..7d8ae5490342d 100644
--- a/src/vs/workbench/browser/parts/editor/editorsObserver.ts
+++ b/src/vs/workbench/browser/parts/editor/editorsObserver.ts
@@ -48,7 +48,7 @@ export class EditorsObserver extends Disposable {
 	}
 
 	get editors(): IEditorIdentifier[] {
-		return this.mostRecentEditorsMap.values();
+		return [...this.mostRecentEditorsMap.values()];
 	}
 
 	hasEditor(resource: URI): boolean {
@@ -283,7 +283,7 @@ export class EditorsObserver extends Disposable {
 
 		// Across all editor groups
 		else {
-			await this.doEnsureOpenedEditorsLimit(limit, this.mostRecentEditorsMap.values(), exclude);
+			await this.doEnsureOpenedEditorsLimit(limit, [...this.mostRecentEditorsMap.values()], exclude);
 		}
 	}
 
@@ -342,7 +342,7 @@ export class EditorsObserver extends Disposable {
 	private serialize(): ISerializedEditorsList {
 		const registry = Registry.as<IEditorInputFactoryRegistry>(Extensions.EditorInputFactories);
 
-		const entries = this.mostRecentEditorsMap.values();
+		const entries = [...this.mostRecentEditorsMap.values()];
 		const mapGroupToSerializableEditorsOfGroup = new Map<IEditorGroup, IEditorInput[]>();
 
 		return {
diff --git a/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts b/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts
index fd1ee7b2abf3b..b95522fd605f2 100644
--- a/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts
+++ b/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts
@@ -791,7 +791,7 @@ export abstract class AbstractTaskService extends Disposable implements ITaskSer
 		if (quickOpenHistoryLimit === 0) {
 			return;
 		}
-		let keys = this._recentlyUsedTasks.keys();
+		let keys = [...this._recentlyUsedTasks.keys()];
 		if (keys.length > quickOpenHistoryLimit) {
 			keys = keys.slice(0, quickOpenHistoryLimit);
 		}
@@ -2323,7 +2323,7 @@ export abstract class AbstractTaskService extends Disposable implements ITaskSer
 				taskMap[key] = task;
 			}
 		});
-		const reversed = recentlyUsedTasks.keys().reverse();
+		const reversed = [...recentlyUsedTasks.keys()].reverse();
 		for (const key in reversed) {
 			let task = taskMap[key];
 			if (task) {