Oilpan: make DocumentFragment a heap allocated object.

R=wibling@chromium.org,zerny@chromium.org,haraken@chromium.org
BUG=357163

Review URL: https://codereview.chromium.org/289273002

git-svn-id: svn://svn.chromium.org/blink/trunk@174382 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Initialize the memory allocated by Vector<IsPod<T>>

For performance reasons
(see https://bugs.webkit.org/show_bug.cgi?id=101649#c5),
Vector used not to initialize the memory allocated for POD
types. This yielded to several use of uninitialized memory
in our code and potentially more of them so it makes sense
to just zero the allocated the memory.

This change just remove the previous initialization so
Vector now initialize the memory to 0 for POD.

BUG=364675,158510

Review URL: https://codereview.chromium.org/291933002

git-svn-id: svn://svn.chromium.org/blink/trunk@174384 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Oilpan: Move XPath::ParseNode, XPath::Step::NodeTest, XPath::Predicate to Oilpan heap.

Note:
- XPathExpression::m_topExpression should be OwnPtr or Member.
  We should avoid manual destruction.
- Parser::parseStatement should return OwnPtr<Expression> because it
  moves the ownership.
- Remove Parser::m_parseNodes, m_predicateVectors, m_expressionVectors,
  and m_nodeTests in enable_oilpan=1.
  They are necessary to keep ownership of objects during parsing.
  We don't need such hacks in Oilpan because such objects are pointed
  from stack.
- Make Path::m_filter and Path::m_path OwnPtrs or Members to avoid
  manual destruction.
- Step::NodeTest was a part object of Step and new/delete were used.
  This CL makes Step::NodeTest GarbageCollectedFinalized, and
  makes no part object.

This is a preparation to move XPath::NodeSet, XPath::ValueData, and
XPath::Value to Oilpan heap, which is necessary to remove
RefPtr<Node> and RefPtr<Attr>.

BUG=357163

Review URL: https://codereview.chromium.org/292103003

git-svn-id: svn://svn.chromium.org/blink/trunk@174385 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove _callSiteStackTrace field from TimelineRecordImpl

callSiteStackTrace should always return async initiator's stack trace.

BUG=None

Review URL: https://codereview.chromium.org/299683003

git-svn-id: svn://svn.chromium.org/blink/trunk@174386 bbb929c8-8fbe-4397-9dbb-9b2b20218538