Eliminate "temporary" and "uninitialized" isolated worlds

Temporary worlds were mostly used by the TestRunner. I've updated all layout
tests to always pass a world ID > 0 (Chromium always passes such an ID).
ASSERTs have been added in many places to check this invariant.

The only remaining usage of these concepts is a hack in ScriptController.
After isolating that hack (which itself should eventually be removed), there
are no other uses of uninitializedWorldId to create temporary (or "weak")
isolated worlds.

R=abarth
BUG=230460

Review URL: https://chromiumcodereview.appspot.com/13954010

git-svn-id: svn://svn.chromium.org/blink/trunk@148291 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Re-enable fast/js/prototype.html

The test is passing (no FAIL in the output), it just needed
a new baseline as the exception message is different on V8.

BUG=26737

Review URL: https://codereview.chromium.org/14175007

git-svn-id: svn://svn.chromium.org/blink/trunk@148292 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove the Network Information API implementation.

The feature is disabled for all of Chromium right now, with no plans
to enable it.

BUG=

Review URL: https://codereview.chromium.org/13820033

git-svn-id: svn://svn.chromium.org/blink/trunk@148293 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Allow CSS box-shadow for native appearance.

IE, Firefox, and Opera(Presto) allow box-shadow for form controls. We should
follow it.

- Remove box-shadow clearing code in RenderTheme*.
- For some appearance, isControlStyled should return true when box-shadow is
  specified. Unless this change, box-shadow is not drawn.

- Add meny pixel tests to check rendering result. This patch doesn't contain
  expectation because codereview.chromium.org doesn't support images.
- Remove fast/forms/box-shadow-override.html. The new tests cover more types.

BUG=92547,96192

Review URL: https://chromiumcodereview.appspot.com/14215002

git-svn-id: svn://svn.chromium.org/blink/trunk@148294 bbb929c8-8fbe-4397-9dbb-9b2b20218538