Revert "Add a release assert in Element's constructor to track down a crasher"

This reverts r164442.

The RELEASE_ASSERT never fired in production, so we might as well remove it.

R=abarth@chromium.org
BUG=312410

Review URL: https://codereview.chromium.org/145263006

git-svn-id: svn://svn.chromium.org/blink/trunk@165779 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove iframe@seamless

This CL removes support for seamless iframes. Seamless iframes were already
behind a runtime flag, which means this CL doesn't have any web exposed
effects. Hopefully someday we'll return to iframe@seamless, but we're currently
investing our efforts elsewhere.

Review URL: https://codereview.chromium.org/138443013

git-svn-id: svn://svn.chromium.org/blink/trunk@165781 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Mark inspector/layer-compositing-reasons.html as timing out

This test will time out after https://codereview.chromium.org/131973020 lands
because content_shell now does a layout after calling the requestAnimationFrame
callbacks, which makes the test environment match the production environment.
Unfortunately, that change causes inspector/layer-compositing-reasons.html to
timeout.  The test appears to rely on the old broken version of
--dump-render-tree's requestAnimationFrame and continually calls
requestAnimationFrame.

BUG=337944
R=esprehn@chromium.org

Review URL: https://codereview.chromium.org/147323002

git-svn-id: svn://svn.chromium.org/blink/trunk@165782 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Make sure the root node of selector queries is a ContainerNode

Make sure the root node of selector queries is a ContainerNode by moving the
querySelector*() methods from the Node class to the ContainerNode class. These
methods are exposed to JS on Document and Element, both of which are
container nodes.

Doing this gets rid of an unnecessary container node check in SelectorQuery
and also enables using the slightly faster firstWithin(ContainerNode) over
firstWithin(Node) traversal method.

R=eseidel, esprehn, adamk

Review URL: https://codereview.chromium.org/138743008

git-svn-id: svn://svn.chromium.org/blink/trunk@165783 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Reduce code duplication in RenderListMarker

Change the suffix/space metric and painting logic in RenderListMarker::
paint to reuse code for the LTR and RTL cases. As a part of this change
the hardcoded direction for constructTextRun can also be removed.

BUG=333004
R=leviw@chromium.org

Review URL: https://codereview.chromium.org/141803013

git-svn-id: svn://svn.chromium.org/blink/trunk@165784 bbb929c8-8fbe-4397-9dbb-9b2b20218538