allow MemberExpressions in for-of head

lib/babel/transformation/transformers/es6/for-of.js

@@ -65,7 +65,7 @@ var loose = function (node, parent, scope, file) {
   var left = node.left;
   var declar, id;
 
-  if (t.isIdentifier(left) || t.isPattern(left)) {
+  if (t.isIdentifier(left) || t.isPattern(left) || t.isMemberExpression(left)) {
     // for (i of test), for ({ i } of test)
     id = left;
   } else if (t.isVariableDeclaration(left)) {
@@ -126,7 +126,7 @@ var spec = function (node, parent, scope, file) {
   var stepKey   = scope.generateUidIdentifier("step");
   var stepValue = t.memberExpression(stepKey, t.identifier("value"));
 
-  if (t.isIdentifier(left) || t.isPattern(left)) {
+  if (t.isIdentifier(left) || t.isPattern(left) || t.isMemberExpression(left)) {
     // for (i of test), for ({ i } of test)
     declar = t.expressionStatement(t.assignmentExpression("=", left, stepValue));
   } else if (t.isVariableDeclaration(left)) {

test/fixtures/transformation/es6-for-of-loose/member-expression/actual.js

@@ -0,0 +1,3 @@
+for (obj.prop of arr) {
+
+}

test/fixtures/transformation/es6-for-of-loose/member-expression/expected.js

@@ -0,0 +1,12 @@
+"use strict";
+
+for (var _iterator = arr, _isArray = Array.isArray(_iterator), _i = 0, _iterator = _isArray ? _iterator : _iterator[Symbol.iterator]();;) {
+  if (_isArray) {
+    if (_i >= _iterator.length) break;
+    obj.prop = _iterator[_i++];
+  } else {
+    _i = _iterator.next();
+    if (_i.done) break;
+    obj.prop = _i.value;
+  }
+}

test/fixtures/transformation/es6-for-of/member-expression/actual.js

@@ -0,0 +1,3 @@
+for (obj.prop of arr) {
+
+}

test/fixtures/transformation/es6-for-of/member-expression/expected.js

@@ -0,0 +1,5 @@
+"use strict";
+
+for (var _iterator = arr[Symbol.iterator](), _step; !(_step = _iterator.next()).done;) {
+  obj.prop = _step.value;
+}