Make form-association for <img> consistent with other form-associated elements.

Form-association for <img> was inconsistent with other form-associated elements.
 - If an <img> element was detached from the document tree, it was always
   disassociateted.
 - If an owner <form> was detached from the document tree but an associated
   <img> remained in the document tree, <img> wasn't disassociated.
This CL fixes them.

Specificatoin:
http://www.whatwg.org/specs/web-apps/current-work/multipage/association-of-controls-and-forms.html#association-of-controls-and-forms

Implementation:

* HTMLImageElement::formOwner:
  We need to fix this in this CL because tests made an assertion failure
in HTMLFormElement::elementFromPastNamesMap.

* HTMLImageElement::formRemovedFromTree:
  Added to fix the second bullet above.

* HTMLImageElement::removedFrom:
  Added common ancestor check to fix the first bullet above.

* HTMLImageElement::resetFormOwner:
  Added to centralize m_form handling.  This is an implementation of
'reset the form owner' steps for non-reassociateable elements.


BUG=336317
TEST=automated

Review URL: https://codereview.chromium.org/141113012

git-svn-id: svn://svn.chromium.org/blink/trunk@165436 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Extract script formatter worker in a separate build target

Files that used by ScriptFormatterWorker exclusively were removed from devtools_files list.

New JS compiler standalone module added.

Drive-by: reformatted copy actions in devtools.gyp for better readability.

BUG=None
R=lushnikov@chromium.org

Review URL: https://codereview.chromium.org/143433002

git-svn-id: svn://svn.chromium.org/blink/trunk@165437 bbb929c8-8fbe-4397-9dbb-9b2b20218538
TimelinePanel: add "Started at" value into Details pane <EOM>

BUG=326121
R=yurys@chromium.org

Review URL: https://codereview.chromium.org/141753011

git-svn-id: svn://svn.chromium.org/blink/trunk@165438 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Test non-crashing updating of worker scope event handlers.

Add a pair of tests to verify that repeatedly updating attribute event
handlers on a worker global scope doesn't fall over.

R=jochen@chromium.org,dslomov@chromium.org
BUG=239669

Review URL: https://codereview.chromium.org/140723002

git-svn-id: svn://svn.chromium.org/blink/trunk@165439 bbb929c8-8fbe-4397-9dbb-9b2b20218538