Store marker identifiers as AtomicString

Marker identifiers can be better stored as AtomicString (like for instance clip-path identifiers) since
they wil llikely share the same value as an id attribute.

Review URL: https://codereview.chromium.org/203723007

git-svn-id: svn://svn.chromium.org/blink/trunk@169556 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: add tooltip for Preserve Log.

BUG=353994

Review URL: https://codereview.chromium.org/196383036

git-svn-id: svn://svn.chromium.org/blink/trunk@169557 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add Element::subResourceAttributeName() virtual function

Add Element::subResourceAttributeName() virtual function to distribute the code
to each HTML class, instead of having a complex function with a lot of branching
to determine the subresource attribute name of an Element.

R=tkent, adamk

Review URL: https://codereview.chromium.org/202633009

git-svn-id: svn://svn.chromium.org/blink/trunk@169558 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Removed dead and obsolete self-inclusions in headers.

BUG=353954

Review URL: https://codereview.chromium.org/203223014

git-svn-id: svn://svn.chromium.org/blink/trunk@169559 bbb929c8-8fbe-4397-9dbb-9b2b20218538