Merge branch 'master' into experimental

# Conflicts:
#	src/babel/transformation/transformers/internal/strict.js

CHANGELOG.md

@@ -13,6 +13,14 @@ _Note: Gaps between patch versions are faulty/broken releases._
 
 See [CHANGELOG - 6to5](CHANGELOG-6to5.md) for the pre-4.0.0 version changelog.
 
+## 4.7.13
+
+ * **Bug Fix**
+  * Handle comments on use strict directives.
+  * Fix assignment patterns with a left side pattern.
+ * **Polish**
+  * Special case `this` when doing expression memoisation.
+
 ## 4.7.12
 
  * **Bug Fix**

package.json

@@ -1,7 +1,7 @@
 {
   "name": "babel",
   "description": "Turn ES6 code into readable vanilla ES5 with source maps",
-  "version": "4.7.12",
+  "version": "4.7.13",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "homepage": "https://babeljs.io/",
   "repository": "babel/babel",

packages/babel-runtime/package.json

@@ -1,7 +1,7 @@
 {
   "name": "babel-runtime",
   "description": "babel selfContained runtime",
-  "version": "4.7.12",
+  "version": "4.7.13",
   "repository": "babel/babel",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "dependencies": {

src/babel/transformation/transformers/es6/destructuring.js

@@ -290,14 +290,21 @@ class DestructuringTransformer {
 
     //
 
-    this.nodes.push(this.buildVariableAssignment(
-      pattern.left,
-      t.conditionalExpression(
-        t.binaryExpression("===", tempValueRef, t.identifier("undefined")),
-        pattern.right,
-        tempValueRef
-      )
-    ));
+    var tempConditional = t.conditionalExpression(
+      t.binaryExpression("===", tempValueRef, t.identifier("undefined")),
+      pattern.right,
+      tempValueRef
+    );
+
+    var left = pattern.left;
+    if (t.isPattern(left)) {
+      this.nodes.push(t.expressionStatement(
+        t.assignmentExpression("=", tempValueRef, tempConditional)
+      ));
+      this.push(left, tempValueRef);
+    } else {
+      this.nodes.push(this.buildVariableAssignment(left, tempConditional));
+    }
   }
 
   pushObjectSpread(pattern, objRef, spreadProp, spreadPropIndex) {

test/fixtures/transformation/es6-destructuring/assignment-expression-pattern/actual.js

@@ -0,0 +1,2 @@
+var z = {};
+var { x: { y } = {} } = z;

test/fixtures/transformation/es6-destructuring/assignment-expression-pattern/expected.js

@@ -0,0 +1,6 @@
+"use strict";
+
+var z = {};
+var _z$x = z.x;
+_z$x = _z$x === undefined ? {} : _z$x;
+var y = _z$x.y;