Add unit tests for TestFile.

Add unit tests for most methods in TestFile. Some cases are
missing, but this should be a good start.

Tweak an import in TestFile to facilitate unit testing.

BUG=

Review URL: https://chromiumcodereview.appspot.com/18272022

git-svn-id: svn://svn.chromium.org/blink/trunk@153533 bbb929c8-8fbe-4397-9dbb-9b2b20218538
document.elementFromPoint doesn't work if text nodes are attached on a ShadowRoot.

In TreeScope::elementFromPoint,
 - nodeFromPoint can return a Text node which is a child of a ShadowRoot. We
   should search ancestors of the ShadowRoot in this case.
 - ancestorInThisScope returns this ShadowRoot if |this| is passed. We should
   handle such case.

BUG=256732

Review URL: https://chromiumcodereview.appspot.com/18613002

git-svn-id: svn://svn.chromium.org/blink/trunk@153534 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove dead code in RLC

R=jamesr@chromium.org
BUG=none

Review URL: https://chromiumcodereview.appspot.com/18272010

git-svn-id: svn://svn.chromium.org/blink/trunk@153535 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add support for 'order' on grid items

The property is used to modify painting order and the order in which
we consider grid items for the auto-flow algorithm.

The code is build on the existing OrderIterator and matches what
flexbox does. Also to avoid adding an extra child walk, refactored
the explicit grid initialization so that we do also initialize the
OrderIterator's Vector. This refactoring saves a child walk as we
now compute both explicit grid's sizes in a single child walk.

BUG=257078
TESTS=fast/css-grid-layout/grid-item-order-auto-flow-resolution.html
      fast/css-grid-layout/grid-item-order-paint-order-expected.html

Review URL: https://chromiumcodereview.appspot.com/18516007

git-svn-id: svn://svn.chromium.org/blink/trunk@153536 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Extract the SVG Filter Reference implementation out of the FilterEffectRenderer into its own type of filter.
This way we don't need to build a FilterEffectRenderer when rendering the SVG reference in the compositor.

(This is a copy of patch set 7 from issue 13984002.  I'd like to land it, but Rietveld won't let me modify someone else's issue, so I've uploaded separately.)

BUG=229714

Review URL: https://chromiumcodereview.appspot.com/14793008

git-svn-id: svn://svn.chromium.org/blink/trunk@153537 bbb929c8-8fbe-4397-9dbb-9b2b20218538