Merge branch 'master' into experimental

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

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;