Stub out registerController() / unregisterController()

This basically hooks up the DOM bindings for navigator.registerController() up to the Blink API. Most of the actual work
will happen in chrome.

BUG=

Review URL: https://chromiumcodereview.appspot.com/23455045

git-svn-id: svn://svn.chromium.org/blink/trunk@157771 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Replace several uses of toWebCoreString() by V8TRYCATCH_FOR_V8STRINGRESOURCE() macro

Replace several uses of toWebCoreString() by V8TRYCATCH_FOR_V8STRINGRESOURCE() macro so
that we return as soon as the string conversion fails and to avoid passing a null
string to the following code.

R=haraken
BUG=

Review URL: https://chromiumcodereview.appspot.com/23526039

git-svn-id: svn://svn.chromium.org/blink/trunk@157772 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Permanently enable AXComputedObjectAttributeCache.

It was never needed by other WebKit ports, but it's always a
performance win for Chromium. It's actually better performance to
just leave it enabled than to wait for Chromium to enable it.

After this lands, we can stop calling the functions to enable and
disable it from Chromium and then remove the API.

BUG=289689

Review URL: https://chromiumcodereview.appspot.com/23648013

git-svn-id: svn://svn.chromium.org/blink/trunk@157773 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Pass isolate to v8::Local<>::New() factory function

Pass isolate to v8::Local<>::New() factory function to avoid implicit calls
to v8::Isolate::GetCurrent().

R=haraken
BUG=263412

Review URL: https://chromiumcodereview.appspot.com/23876015

git-svn-id: svn://svn.chromium.org/blink/trunk@157774 bbb929c8-8fbe-4397-9dbb-9b2b20218538