Add a UseCounter for HTMLHeadElement.profile

http://whatwg.org/html#htmlheadelement

The profile attribute is not in the spec and not supported by
Opera 12.16 or Firefox Nightly. It is supported by IE11 Release
Preview. Add a counter to see if we can remove it.

IE11 reflects null as 'null', not '', but leave that for now.

BUG=none

Review URL: https://codereview.chromium.org/101433002

git-svn-id: svn://svn.chromium.org/blink/trunk@163097 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add new helper VTTParser::collectDigitsToInt

Since most uses of VTTParser::collectDigits is followed by a call to
String::toInt on the resulting string, add this new helper with the
aim of later removing the temporary string construction.
Handle overflow in the string-to-int conversion by means of saturation.
(The latter is the intended change of semantics.)

Replace uses of collectDigits with collectDigitsToInt where applicable.
After doing this, there remain no callers to collectDigits outside of
VTTParser, so make the function static.

Also move VTTParser::skipWhiteSpace "textually" to group it with the other
'scanning' functions, and make it static since it does not depend on any
VTTParser state.

BUG=305317

Review URL: https://codereview.chromium.org/101513002

git-svn-id: svn://svn.chromium.org/blink/trunk@163098 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Introduce Debugger.StackTrace structure in protocol.json

This will be used to send async traces from backend to front-end.

BUG=272416
R=pfeldman@chromium.org, yurys@chromium.org

Review URL: https://codereview.chromium.org/98953004

git-svn-id: svn://svn.chromium.org/blink/trunk@163099 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Fix perf regression on vnexpress.net.

The regression is from http://src.chromium.org/viewvc/blink?revision=162662&view=revision.
The problem was that we were throwing away the StyleResolver
if there was a forced pending recalc. Instead, early return
after the compareStyleSheets call, but before the expensive
StyleInvalidationAnalysis.

BUG=324908

Review URL: https://codereview.chromium.org/100113002

git-svn-id: svn://svn.chromium.org/blink/trunk@163100 bbb929c8-8fbe-4397-9dbb-9b2b20218538