[es6] Fix bug in pattern re-writing

test/mjsunit/es6/destructuring.js

Index: test/mjsunit/es6/destructuring.js
diff --git a/test/mjsunit/es6/destructuring.js b/test/mjsunit/es6/destructuring.js
index d15805711f0a82324acbeee48f57c0f69da73307..1f16c45270a9574d22f60865fbe1ca0377eb40e3 100644
--- a/test/mjsunit/es6/destructuring.js
+++ b/test/mjsunit/es6/destructuring.js
@@ -260,6 +260,63 @@
 }());
 
 
+(function TestAssignmentExprInInitializers() {
+  {
+    let x, y;
+    {
+      let { x = y = 1 } = {};
+      assertSame(x, 1);
+      assertSame(y, 1);
+    }
+    assertSame(undefined, x);
+    assertSame(1, y);
+  }
+
+  {
+    let x, y;
+    {
+      let { x: x = y = 1 } = {};
+      assertSame(1, x);
+      assertSame(1, y);
+    }
+    assertSame(undefined, x);
+    assertSame(1, y);
+  }
+
+  {
+    let x, y;
+    {
+      let [ x = y = 1 ] = [];
+      assertSame(1, x);
+      assertSame(1, y);
+    }
+    assertSame(undefined, x);
+    assertSame(1, y);
+  }
+
+  {
+    let x, y;
+    (function({ x = y = 1 }) {}({}));
+    assertSame(undefined, x);
+    assertSame(1, y);
+  }
+
+  {
+    let x, y;
+    (function({ x: x = y = 1 }) {}({}));
+    assertSame(undefined, x);
+    assertSame(1, y);
+  }
+
+  {
+    let x, y;
+    (function([ x = y = 1 ]) {}([]));
+    assertSame(undefined, x);
+    assertSame(1, y);
+  }
+}());
+
+
 (function TestMultipleAccesses() {
   assertThrows(
     "'use strict';"+