Remove calls to HandleScope default ctor.

It's replaced by a version which takes an isolate. The default ctor will be removed soon.

BUG=

Review URL: https://chromiumcodereview.appspot.com/23788005

git-svn-id: svn://svn.chromium.org/blink/trunk@157217 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Support for Web Notifications should always be compiled in.

This patch removes the ENABLE_NOTIFICATIONS compile time define. The
ENABLE_LEGACY_NOTIFICATIONS define continues to exist and will be
disabled for Android, but enabled on all other platforms.

Removing ENABLE_NOTIFICATIONS increases the Android apk size in
Release mode by 8.3KB. When ENABLE_LEGACY_NOTIFICATIONS also is
enabled, the increase amounts to 11.6KB.

BUG=115320

Review URL: https://chromiumcodereview.appspot.com/23441030

git-svn-id: svn://svn.chromium.org/blink/trunk@157218 bbb929c8-8fbe-4397-9dbb-9b2b20218538