feat($parse): support trailing commas in object & array literals

Per ECMAScript 5.1 specification trailing commas are allowed in object and
array literals. All modern browsers as well as IE>8 support this syntax.
This commit adds support for such syntax to Angular expressions.

Author: mgol

src/ng/parse.js

@@ -785,6 +785,10 @@ Parser.prototype = {
     var allConstant = true;
     if (this.peekToken().text !== ']') {
       do {
+        if (this.peek(']')) {
+          // Support trailing commas per ES5.1.
+          break;
+        }
         var elementFn = this.expression();
         elementFns.push(elementFn);
         if (!elementFn.constant) {
@@ -811,6 +815,10 @@ Parser.prototype = {
     var allConstant = true;
     if (this.peekToken().text !== '}') {
       do {
+        if (this.peek('}')) {
+          // Support trailing commas per ES5.1.
+          break;
+        }
         var token = this.expect(),
         key = token.string || token.text;
         this.consume(':');

test/ng/parseSpec.js

@@ -460,6 +460,8 @@ describe('parser', function() {
           expect(scope.$eval("[1, 2]").length).toEqual(2);
           expect(scope.$eval("[1, 2]")[0]).toEqual(1);
           expect(scope.$eval("[1, 2]")[1]).toEqual(2);
+          expect(scope.$eval("[1, 2,]")[1]).toEqual(2);
+          expect(scope.$eval("[1, 2,]").length).toEqual(2);
         });
 
         it('should evaluate array access', function() {
@@ -474,6 +476,9 @@ describe('parser', function() {
           expect(toJson(scope.$eval("{a:'b'}"))).toEqual('{"a":"b"}');
           expect(toJson(scope.$eval("{'a':'b'}"))).toEqual('{"a":"b"}');
           expect(toJson(scope.$eval("{\"a\":'b'}"))).toEqual('{"a":"b"}');
+          expect(toJson(scope.$eval("{a:'b',}"))).toEqual('{"a":"b"}');
+          expect(toJson(scope.$eval("{'a':'b',}"))).toEqual('{"a":"b"}');
+          expect(toJson(scope.$eval("{\"a\":'b',}"))).toEqual('{"a":"b"}');
         });
 
         it('should evaluate object access', function() {