Fix PinchViewport::visibleRectInDocument

Fix PinchViewport::visibleRectInDocument

This method needs to return the visual viewport rect relative to the document
origin. Introducing the RootFrameViewport in r194957 meant that
frameView->scrollableArea()->scrollPositionDouble() went from being the offset
of just the layout viewport to being the visual viewport offset. This method
wasn't updated at the time so it erroneously moves the returned offset by the
visual viewport offset.


BUG=

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197473

[bokan, 2015-06-17 20:05:06]

bokan@chromium.org changed reviewers:
+ mustaq@chromium.org

[bokan, 2015-06-17 20:09:15]

Hi Mustaq, ptal. The scrollPositionDouble call in this method calls
RootFrameViewport::scrollPositionDouble
https://code.google.com/p/chromium/codesearch/#chromium/src/third_party/WebKi...


As you can see, it adds visualViewport().scrollPositionDouble() but then in
PinchViewport::visibleRectInDocument we move the visibleRect by the result so we
include visualViewport().scrollPositionDouble() twice.

[bokan, 2015-06-18 19:29:03]

The CQ bit was checked by bokan@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-06-18 19:29:52]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1178273008/1

[commit-bot: I haz the power, 2015-06-18 20:58:28]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-06-18 20:58:29]

Dry run: This issue passed the CQ dry run.

[mustaq, 2015-06-19 13:58:05]

lgtm

[bokan, 2015-06-19 14:30:32]

The CQ bit was checked by bokan@chromium.org

[commit-bot: I haz the power, 2015-06-19 14:30:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1178273008/1

[commit-bot: I haz the power, 2015-06-19 14:34:38]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197473