Bug 912121 - Migrate major DevTools directories. rs=devtools

Move major DevTools files to new directories using the following steps:

hg mv browser/devtools devtools/client
hg mv toolkit/devtools/server devtools/server
hg mv toolkit/devtools devtools/shared

No other changes are made.

devtools/client/webconsole/test/test-bug-766001-js-errors.js

@@ -0,0 +1,7 @@
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+window.addEventListener("load", function() {
+  document.bar();
+}, false);