[DevTools] Fix one more backwards compatibility breakage.

With recent changes, it's dangerous to inject /deep/ selectors
to the page, as they get high priority. This patch stops injecting
backwards compatilibity code to the all-new frontned.

BUG=none

Review URL: https://codereview.chromium.org/1310653003

git-svn-id: svn://svn.chromium.org/blink/trunk@201106 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/devtools/front_end/devtools.js

@@ -782,6 +782,9 @@ window.InspectorFrontendHost = new InspectorFrontendHostImpl();
  */
 function installBackwardsCompatibility()
 {
+    if (window.location.search.indexOf("remoteFrontend") === -1)
+        return;
+
     /**
      * @this {CSSStyleDeclaration}
      */