6.0.0

I'm extremely stupid and didn't commit as I go. To anyone reading this
I'm extremely sorry. A lot of these changes are very broad and I plan on
releasing Babel 6.0.0 today live on stage at Ember Camp London so I'm
afraid I couldn't wait. If you're ever in London I'll buy you a beer
(or assorted beverage!) to make up for it, also I'll kiss your feet and
give you a back massage, maybe.

packages/babel-plugin-transform-es2015-classes/src/lib/memoise-decorators.js

@@ -0,0 +1,39 @@
+/* @flow */
+
+import type { Scope } from "babel-traverse";
+import * as t from "babel-types";
+
+export default function (decorators: Array<Object>, scope: Scope): Array<Object> {
+  for (let decorator of decorators) {
+    let expression = decorator.expression;
+    if (!t.isMemberExpression(expression)) continue;
+
+    let temp = scope.maybeGenerateMemoised(expression.object);
+    let ref;
+
+    let nodes = [];
+
+    if (temp) {
+      ref = temp;
+      nodes.push(t.assignmentExpression("=", temp, expression.object));
+    } else {
+      ref = expression.object;
+    }
+
+    nodes.push(t.callExpression(
+      t.memberExpression(
+        t.memberExpression(ref, expression.property, expression.computed),
+        t.identifier("bind")
+      ),
+      [ref]
+    ));
+
+    if (nodes.length === 1) {
+      decorator.expression = nodes[0];
+    } else {
+      decorator.expression = t.sequenceExpression(nodes);
+    }
+  }
+
+  return decorators;
+}