Oilpan: Move compile-time verification to the trace methods for Member
and Persistent instead of constructors.

We should be able to have Member pointers for forward declared types.
At this point we cannot because the compile-time asserts will fail
because the templates will not be able to determine that the type
in the Member is garbage collected.

The plugin will force us to trace all Members on heap-allocated
classes. Therefore, the trace method will be instantiated in all
cases that matter and therefore we should get the same level of
checking by moving the compile-time asserts to the trace method.
The trace methods need the full definition of the types, so at
that point it is safe to use the templates to determine if a
type is garbage collected.

This issue was encountered while working on moving the Node
hierarchy to RefCountedGarbageCollected instead of TreeShared.

R=zerny@chromium.org,erik.corry@gmail.com, haraken@chromium.org, wibling@chromium.org

Review URL: https://codereview.chromium.org/256623013

git-svn-id: svn://svn.chromium.org/blink/trunk@172906 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Ensure style resolver is created to avoid crash.

The style resolver may be cleared by DOM modifications in event handlers
prior to changing the :focus/:active/:hover state. Use ensureStyleResolver()
instead of just styleResolver() to make sure its created to be able to
schedule style invalidations.

R=esprehn@chromium.org
BUG=368017,368026

Review URL: https://codereview.chromium.org/259213002

git-svn-id: svn://svn.chromium.org/blink/trunk@172907 bbb929c8-8fbe-4397-9dbb-9b2b20218538