feat(transpiler): Transform for..of to Dart as for..in

fixes #53

tools/transpiler/spec/fixtures/facade.dart

@@ -1,3 +1,16 @@
+import 'dart:collection';
+
 class MapWrapper {
 
-}
+}
+
+/**
+ * Generic iterable class to test for-of.  Provides iteration of the given list.
+ */
+class IterableList extends IterableBase {
+  List values;
+  IterableList(values) {
+    this.values = values;
+  }
+  Iterator get iterator => values.iterator;
+}

tools/transpiler/spec/fixtures/facade.es6

@@ -1,3 +1,18 @@
 export class MapWrapper {
 
-}
+}
+
+/**
+ * Generic iterable class to test for-of.  Provides iteration of the given array.
+ */
+export class IterableList {
+  constructor(values) {
+    this.values = values;
+  }
+
+  *[Symbol.iterator]() {
+    for (var value of this.values) {
+      yield value;
+    }
+  }
+}

tools/transpiler/spec/for_of_spec.js

@@ -0,0 +1,51 @@
+import {describe, it, expect} from 'test_lib/test_lib';
+import {ListWrapper, MapWrapper} from 'facade/collection';
+import {IterableList} from './fixtures/facade';
+
+export function main() {
+  describe('for..of', function() {
+    it('should iterate iterable', function() {
+      var values = ['a', 'b', 'c'];
+      var result = ListWrapper.create();
+      for (var value of new IterableList(values)) {
+        ListWrapper.push(result, value);
+      }
+      expect(result).toEqual(values);
+    });
+
+    it('should iterate iterable without var declaration list', function() {
+      var values = ['a', 'b', 'c'];
+      var result = ListWrapper.create();
+      var value;
+      for (value of new IterableList(values)) {
+        ListWrapper.push(result, value);
+      }
+      expect(value).toEqual('c');
+      expect(result).toEqual(values);
+    });
+
+    it('should iterate maps', function() {
+      var values = [['a', 1], ['b', 2], ['c', 3]];
+      var result = ListWrapper.create();
+      var map = MapWrapper.createFromPairs(values);
+      for (var [key, value] of MapWrapper.iterable(map)) {
+        ListWrapper.push(result, [key, value]);
+      }
+      expect(result).toEqual(values);
+    });
+
+    it('should iterate maps without var declaration list', function() {
+      var values = [['a', 1], ['b', 2], ['c', 3]];
+      var result = ListWrapper.create();
+      var map = MapWrapper.createFromPairs(values);
+      var key, value;
+      for ([key, value] of MapWrapper.iterable(map)) {
+        ListWrapper.push(result, [key, value]);
+      }
+      expect(key).toEqual('c');
+      expect(value).toEqual(3);
+      expect(result).toEqual(values);
+    });
+  });
+}
+