Layout Test for selecting text ignoring region content

Patch already landed in WebKit. See http://trac.webkit.org/changeset/156962

Add new reftests for selecting text in texts wrapping a region, where
the region content is ignored. It compares the behavior (highlighted
text and selected content) in regions and absolute positions.

Absolute positioned elements do not fill the gaps on the right during
the selection, unlike regular elements. This is the reason why some
regular elements are floated in order to avoid such problems in the
reftests.

Provided layout tests for different writing models.

Review URL: https://codereview.chromium.org/34863002

git-svn-id: svn://svn.chromium.org/blink/trunk@160550 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Deflake 3 SVG tests that (tried to) use Ahem

This is an experimental patch to de-flake the following tests:
  svg/custom/repaint-shadow.svg
  svg/zoom/page/zoom-zoom-coords.xhtml
  svg/custom/font-face-cascade-order.svg

Each of these tests references Ahem and is flaky on OSX. In this
patch I've explicitly included Ahem via CSS so we don't rely on
the OSX font cache.

svg/custom/repaint-shadow.svg now requires a rebaseline because
the font now loads and causes some additional repainting.
The actual test is unaffected.

svg/zoom/page/zoom-zoom-coords.xhtml requires a rebaseline
because the Ahem font was not used at all before.

If this deflake works, an additional 5 SVG tests that reference
Ahem can also be deflaked.

Follow along the deflakification at
http://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=svg/custom/repaint-shadow.svg,svg/zoom/page/zoom-zoom-coords.xhtml,svg/custom/font-face-cascade-order.svg

BUG=311469

Review URL: https://codereview.chromium.org/43273002

git-svn-id: svn://svn.chromium.org/blink/trunk@160551 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Internals::includerFor() is no longer required.

Element.getDestinationInsertionPoints() can replace Internals::includerFor().

BUG=None
TEST=Update the existing test.

Review URL: https://codereview.chromium.org/32443003

git-svn-id: svn://svn.chromium.org/blink/trunk@160552 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Give Document its own LifecycleContext

This change makes Document inherits LifecycleContext<Document>.

Note that this means that Document implements not onlly LC<Document>,
but also LC<ExecutionContext> through its superclass.
To make this multi-LC class work, this change modifies
createLifecycleNotifier() signature.
New signature is unique per LC instatiations.
Also, thanks for the parameterized type, it is no longer need to be
virtual.

At last this change turns some classes from ContextLifecycleObserver
to DocumentLifecycleObserver. This is just because these classes
are bound to Document and never bound to Worker.

R=abarth, tkent, dglazkov
BUG=305497

Review URL: https://codereview.chromium.org/37773006

git-svn-id: svn://svn.chromium.org/blink/trunk@160553 bbb929c8-8fbe-4397-9dbb-9b2b20218538