refactor(skipWhile): remove thisArg argument

- removes thisArg and tests around that from skipWhile
- removes extra thisArg on interface defs for first and last as well

BREAKING CHANGE: skipWhile no longer accepts a thisArg argument
related #878

spec/operators/skipWhile-spec.js

@@ -160,23 +160,6 @@ describe('Observable.prototype.skipWhile()', function () {
     expectSubscriptions(source.subscriptions).toBe(sourceSubs);
   });
 
-  it('should accept a thisArg', function () {
-    var source = hot('-1-^--2--3--4--5--6--|');
-    var sourceSubs =    '^                 !';
-    var expected =      '---------4--5--6--|';
-
-    function Skiper() {
-      this.doSkip = function (v) { return +v < 4; };
-    }
-
-    var skiper = new Skiper();
-
-    expectObservable(
-      source.skipWhile(function (v) { return this.doSkip(v); }, skiper)
-    ).toBe(expected);
-    expectSubscriptions(source.subscriptions).toBe(sourceSubs);
-  });
-
   it('should handle Observable.empty', function () {
     var source = cold('|');
     var subs =        '(^!)';

src/CoreOperators.ts

@@ -30,7 +30,7 @@ export interface CoreOperators<T> {
   filter?: (predicate: (x: T) => boolean, ix?: number, thisArg?: any) => Observable<T>;
   finally?: (finallySelector: () => void) => Observable<T>;
   first?: <R>(predicate?: (value: T, index: number, source: Observable<T>) => boolean,
-              resultSelector?: (value: T, index: number) => R, thisArg?: any, defaultValue?: any) => Observable<T> | Observable<R>;
+              resultSelector?: (value: T, index: number) => R, defaultValue?: any) => Observable<T> | Observable<R>;
   flatMap?: <R>(project: ((x: T, ix: number) => Observable<any>),
                 projectResult?: (x: T, y: any, ix: number, iy: number) => R,
                 concurrent?: number) => Observable<R>;
@@ -41,7 +41,7 @@ export interface CoreOperators<T> {
   ignoreElements?: () => Observable<T>;
   last?: <R>(predicate?: (value: T, index: number) => boolean,
              resultSelector?: (value: T, index: number) => R,
-             thisArg?: any, defaultValue?: any) => Observable<T> | Observable<R>;
+             defaultValue?: any) => Observable<T> | Observable<R>;
   every?: (predicate: (value: T, index: number) => boolean, thisArg?: any) => Observable<T>;
   map?: <R>(project: (x: T, ix?: number) => R, thisArg?: any) => Observable<R>;
   mapTo?: <R>(value: R) => Observable<R>;
@@ -69,7 +69,7 @@ export interface CoreOperators<T> {
   single?: (predicate?: (value: T, index: number) => boolean) => Observable<T>;
   skip?: (count: number) => Observable<T>;
   skipUntil?: (notifier: Observable<any>) => Observable<T>;
-  skipWhile?: (predicate: (x: T, index: number) => boolean, thisArg?: any) => Observable<T>;
+  skipWhile?: (predicate: (x: T, index: number) => boolean) => Observable<T>;
   startWith?: (x: T) => Observable<T>;
   subscribeOn?: (scheduler: Scheduler, delay?: number) => Observable<T>;
   switch?: () => Observable<T>;

src/operator/skipWhile.ts

@@ -3,17 +3,13 @@ import {Operator} from '../Operator';
 import {Subscriber} from '../Subscriber';
 import {tryCatch} from '../util/tryCatch';
 import {errorObject} from '../util/errorObject';
-import {bindCallback} from '../util/bindCallback';
 
-export function skipWhile<T>(predicate: (x: T, index: number) => boolean, thisArg?: any): Observable<T> {
-  return this.lift(new SkipWhileOperator(predicate, thisArg));
+export function skipWhile<T>(predicate: (x: T, index: number) => boolean): Observable<T> {
+  return this.lift(new SkipWhileOperator(predicate));
 }
 
 class SkipWhileOperator<T, R> implements Operator<T, R> {
-  private predicate: (x: T, index: number) => boolean;
-
-  constructor(predicate: (x: T, index: number) => boolean, thisArg?: any) {
-    this.predicate = <(x: T, index: number) => boolean>bindCallback(predicate, thisArg, 2);
+  constructor(private predicate: (x: T, index: number) => boolean) {
   }
 
   call(subscriber: Subscriber<T>): Subscriber<T> {