createV8HTMLFallbackWrapper() bypassing bindings integrity check.

The generated code is calling the underlying createWrapper() method, rather than the higher-level wrap() method, which performs the bindings integrity check.  So move the check down to the lower level function to avoid bypasses both now and in the future.

Doing so kicked out one other place where objects are not properly wrapped, for the partially-implemented GestureEvent class.  It must not advertise an interface name that isn't yet present in IDL.

BUG=260324

Review URL: https://chromiumcodereview.appspot.com/19264002

git-svn-id: svn://svn.chromium.org/blink/trunk@154320 bbb929c8-8fbe-4397-9dbb-9b2b20218538