document.documentElement.scrollTop/Left is zero

Blink, as of today, is the only engine that does not respect the
specification with regards to the values returned from scrollTop
and scrollLeft properties of documentElement and body nodes.

Current behavior is: in both strict and quirks modes, documentElement.scrollTop
always returns 0, while body.scrollTop always returns scrollY.
The analogy behavior applies to scrollLeft and scrollX (the return).

This patch fixes Blink's behavior in accordance to specification [1]:
if a document is in strict mode, document.documentElement.scrollTop
should return 'scrollY', and document.body.scrollTop should return 0.
On the other hand, if it is in quirks mode, document.documentElement
should return 0, and document.body.scrollTop should return 'scrollY'.
Same analogy applies to scrollLeft property.

An optimistic approach was chosen to fix this in the sense of doing this
change without collecting usage data first. The rationale behind it is
that given that Blink is the only engine behavior'ing differently, relevant
WebSites would already have two codepaths.

[1] http://dev.w3.org/csswg/cssom-view/#dom-element-scrolltop

Test: fast/dom/Element/scrollTop-scrollLeft-strict-quirks-modes.html
Existing updated tests:
      fast/dom/anchor-without-content.html
      fast/events/mouse-cursor-image-set.html
      fast/events/mouse-cursor.html
      fast/events/touch/gesture/touch-gesture-fully-scrolled-iframe-propagates.html
      fast/events/touch/gesture/touch-gesture-noscroll-body-propagated.html
      fast/events/touch/gesture/touch-gesture-noscroll-body-xhidden.html
      fast/events/touch/gesture/touch-gesture-noscroll-body-yhidden.html
      fast/events/touch/gesture/touch-gesture-scroll-iframe-editable.html
      fast/events/touch/gesture/touch-gesture-scroll-iframe-not-propagated.html
      fast/events/touch/gesture/touch-gesture-scroll-page-propagated.html
      fast/events/touch/gesture/touch-gesture-scroll-page.html
      fast/scrolling/hover-during-scroll.html
      http/tests/navigation/resources/frame-with-anchor-same-origin.html
      http/tests/navigation/resources/frame-with-anchor.html

BUG=157855

Review URL: https://codereview.chromium.org/25039006

git-svn-id: svn://svn.chromium.org/blink/trunk@158719 bbb929c8-8fbe-4397-9dbb-9b2b20218538
MediaStream API: Adding ExtraData functionality to WebMediaStreamTrack
As part of the work to make Tracks more standalone we need ExtraData functionality in WebMediaStreamTrack.

BUG=294145

Review URL: https://codereview.chromium.org/24535002

git-svn-id: svn://svn.chromium.org/blink/trunk@158720 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: FlameChart follow-up fix for r158718. Do not show EntryInfo if there is no entry under cursor.

BUG=none
R=yurys@chromium.org

Review URL: https://codereview.chromium.org/25727002

git-svn-id: svn://svn.chromium.org/blink/trunk@158722 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Initial iframe load shouldn't add session history item.

This CL is fixing the behavior of setReplacesCurrentHistoryItem for initial frame navigation. The Chromium side change is at  https://codereview.chromium.org/15294012/.

BUG=178380

Review URL: https://codereview.chromium.org/25269006

git-svn-id: svn://svn.chromium.org/blink/trunk@158723 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Rename RenderMediaControlsChromium to RenderMediaControls

The original RenderMediaControls was removed in a previous commit.

BUG=302500

Review URL: https://codereview.chromium.org/25699002

git-svn-id: svn://svn.chromium.org/blink/trunk@158724 bbb929c8-8fbe-4397-9dbb-9b2b20218538