[SVG] animateMotion is freezing at the end by default

Need to mark the renderer for layout after doing a reset of the transform at the end of the animation.
Otherwise transform will not be applied.

R=pdr@chromium.org, schenney@chromium.org, dschulze@chromium.org, fmalita@chromium.org
BUG=265835

Review URL: https://chromiumcodereview.appspot.com/21262002

git-svn-id: svn://svn.chromium.org/blink/trunk@155209 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Early return in markContainingBlocksForLayout if selfNeedsLayout.

This is just a performance optimization. This will be useful as we get rid
of setNeedsLayout(MarkOnlyThis) calls.

Review URL: https://chromiumcodereview.appspot.com/21142005

git-svn-id: svn://svn.chromium.org/blink/trunk@155212 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Move loadOrRedirectSubframe and loadSubframe into HTMLFrameOwnerElement and delete SubframeLoader

loadOrRedirectSubframe is the only remaining public function on SubframeLoader. It's called by both HTMLFrameElementBase and HTMLPluginImageElement, so it needs to go on HTMLFrameOwnerElement.

Review URL: https://chromiumcodereview.appspot.com/20723007

git-svn-id: svn://svn.chromium.org/blink/trunk@155213 bbb929c8-8fbe-4397-9dbb-9b2b20218538
setCompositionFromExistingText() causes two calls to AutofillClient.

Due to the way setCompositionFromExistingText was implemented it was triggering
two textChange updates due to a call to execCommand("delete"). This call is not
needed as setComposition replaces the selection anyway.

BUG=263453

Review URL: https://chromiumcodereview.appspot.com/21052005

git-svn-id: svn://svn.chromium.org/blink/trunk@155216 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Fix overlap testing of negative z-index compositing elements

This patch fixes a bug where negative z-index elements were skipping
checking composited content behind them.

Additionally, more comments were added, and
pushCompositingContainer/popCompositingContainer is renamed to
beginNewOverlapTestingContext/finishCurrentOverlapTestingContenxt.
The push/pop concept is actually misleading because state after
popping is not the same as before pushing.

BUG=264970

Review URL: https://chromiumcodereview.appspot.com/20872002

git-svn-id: svn://svn.chromium.org/blink/trunk@155217 bbb929c8-8fbe-4397-9dbb-9b2b20218538