fix: explictly declare types for mixin base classes (#12876)

As of TypeScript 2.9, tsc will inline imports for inferred types with
the `import("...")` syntax. However, this inlining happens *after*
`paths` are resolved. This means that in places where we import from
`@angular/material/core` in source end up having relative paths (e.g.
`../core/common-behaviors/index`) in the generated d.ts files. These
relative import paths become incorrect when moved into our package
structure, breaking downstream apps.

package.json

@@ -27,13 +27,13 @@
   "version": "6.4.6",
   "requiredAngularVersion": ">=6.0.0 <7.0.0",
   "dependencies": {
-    "@angular/animations": "^6.1.0",
-    "@angular/common": "^6.1.0",
-    "@angular/compiler": "^6.1.0",
-    "@angular/core": "^6.1.0",
-    "@angular/elements": "^6.1.0",
-    "@angular/forms": "^6.1.0",
-    "@angular/platform-browser": "^6.1.0",
+    "@angular/animations": "7.0.0-beta.3",
+    "@angular/common": "7.0.0-beta.3",
+    "@angular/compiler": "7.0.0-beta.3",
+    "@angular/core": "7.0.0-beta.3",
+    "@angular/elements": "7.0.0-beta.3",
+    "@angular/forms": "7.0.0-beta.3",
+    "@angular/platform-browser": "7.0.0-beta.3",
     "@webcomponents/custom-elements": "^1.1.0",
     "core-js": "^2.4.1",
     "rxjs": "^6.2.0",
@@ -45,13 +45,13 @@
   "devDependencies": {
     "@angular-devkit/core": "^0.7.1",
     "@angular-devkit/schematics": "^0.7.1",
-    "@angular/bazel": "^6.1.0",
-    "@angular/compiler-cli": "^6.1.0",
-    "@angular/http": "^6.1.0",
-    "@angular/platform-browser-dynamic": "^6.1.0",
-    "@angular/platform-server": "^6.1.0",
-    "@angular/router": "^6.1.0",
-    "@angular/upgrade": "^6.1.0",
+    "@angular/bazel": "7.0.0-beta.3",
+    "@angular/compiler-cli": "7.0.0-beta.3",
+    "@angular/http": "7.0.0-beta.3",
+    "@angular/platform-browser-dynamic": "7.0.0-beta.3",
+    "@angular/platform-server": "7.0.0-beta.3",
+    "@angular/router": "7.0.0-beta.3",
+    "@angular/upgrade": "7.0.0-beta.3",
     "@bazel/ibazel": "0.3.1",
     "@google-cloud/storage": "^1.1.1",
     "@octokit/rest": "^15.9.4",

src/cdk/table/can-stick.ts

@@ -31,14 +31,16 @@ export interface CanStick {
   resetStickyChanged(): void;
 }
 
+/** @docs-private */
+export type CanStickCtor = Constructor<CanStick>;
+
 /**
  * Mixin to provide a directive with a function that checks if the sticky input has been
  * changed since the last time the function was called. Essentially adds a dirty-check to the
  * sticky value.
  * @docs-private
  */
-export function mixinHasStickyInput<T extends Constructor<{}>>(base: T):
-    Constructor<CanStick> & T {
+export function mixinHasStickyInput<T extends Constructor<{}>>(base: T): CanStickCtor & T {
   return class extends base {
     /** Whether sticky positioning should be applied. */
     get sticky(): boolean { return this._sticky; }

src/cdk/table/cell.ts

@@ -6,9 +6,10 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {ContentChild, Directive, ElementRef, Input, TemplateRef} from '@angular/core';
 import {coerceBooleanProperty} from '@angular/cdk/coercion';
-import {CanStick, mixinHasStickyInput} from './can-stick';
+import {ContentChild, Directive, ElementRef, Input, TemplateRef} from '@angular/core';
+import {CanStick, CanStickCtor, mixinHasStickyInput} from './can-stick';
+
 
 /** Base interface for a cell definition. Captures a column's cell template definition. */
 export interface CellDef {
@@ -45,7 +46,8 @@ export class CdkFooterCellDef implements CellDef {
 // Boilerplate for applying mixins to CdkColumnDef.
 /** @docs-private */
 export class CdkColumnDefBase {}
-export const _CdkColumnDefBase = mixinHasStickyInput(CdkColumnDefBase);
+export const _CdkColumnDefBase: CanStickCtor & typeof CdkColumnDefBase =
+    mixinHasStickyInput(CdkColumnDefBase);
 
 /**
  * Column definition for the CDK table.

src/cdk/table/row.ts

@@ -20,8 +20,8 @@ import {
   ViewContainerRef,
   ViewEncapsulation,
 } from '@angular/core';
+import {CanStick, CanStickCtor, mixinHasStickyInput} from './can-stick';
 import {CdkCellDef, CdkColumnDef} from './cell';
-import {CanStick, mixinHasStickyInput} from './can-stick';
 
 /**
  * The row template that can be used by the mat-table. Should not be used outside of the
@@ -76,7 +76,8 @@ export abstract class BaseRowDef implements OnChanges {
 // Boilerplate for applying mixins to CdkHeaderRowDef.
 /** @docs-private */
 export class CdkHeaderRowDefBase extends BaseRowDef {}
-export const _CdkHeaderRowDefBase = mixinHasStickyInput(CdkHeaderRowDefBase);
+export const _CdkHeaderRowDefBase: CanStickCtor & typeof CdkHeaderRowDefBase =
+    mixinHasStickyInput(CdkHeaderRowDefBase);
 
 /**
  * Header row definition for the CDK table.
@@ -101,7 +102,8 @@ export class CdkHeaderRowDef extends _CdkHeaderRowDefBase implements CanStick, O
 // Boilerplate for applying mixins to CdkFooterRowDef.
 /** @docs-private */
 export class CdkFooterRowDefBase extends BaseRowDef {}
-export const _CdkFooterRowDefBase = mixinHasStickyInput(CdkFooterRowDefBase);
+export const _CdkFooterRowDefBase: CanStickCtor & typeof CdkFooterRowDefBase =
+    mixinHasStickyInput(CdkFooterRowDefBase);
 
 /**
  * Footer row definition for the CDK table.