Oilpan: Move core/xml/ to oilpan's heap

This CL moves DOMParser, XMLHttpRequest, XMLSerializer, XPathEvaluator, XPathExpression, XPathNSResolver, XPathResult, XSLTProcessor to oilpan's heap.

XMLHttpRequest can be used by workers, so I added XMLHttpRequest to USED_FROM_MULTIPLE_THREADS. I'm not sure if workers can touch XMLSerializer, XPathResult etc, but I added them to USED_FROM_MULTIPLE_THREADS just in case. (We'll remove USED_FROM_MULTIPLE_THREADS soon.)

BUG=341032

Review URL: https://codereview.chromium.org/166903010

git-svn-id: svn://svn.chromium.org/blink/trunk@167459 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: fix clunky element update in Elements Panel

This patch additionally refreshes elements title when changes happen to
its children.

BUG=344201

Review URL: https://codereview.chromium.org/168873002

git-svn-id: svn://svn.chromium.org/blink/trunk@167460 bbb929c8-8fbe-4397-9dbb-9b2b20218538