Oilpan: Do not repeatedly memset the same free list memory with zeroes.

The freelists are rebuild during sweeping, so all memory that is on
a freelist when we start sweeping will be needlessly memset.

Instead zero out the memory during sweeping when we know that memory
has become free.

This brings the time spent in memset from ~10% to ~3% on
EventsDispatchingInDeeplyNestedShadowTrees.

R=haraken@chromium.org, oilpan-reviews@chromium.org, wibling@chromium.org, zerny@chromium.org

Review URL: https://codereview.chromium.org/381053002

git-svn-id: svn://svn.chromium.org/blink/trunk@177844 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Activity Logger Refactoring.

Enable Activity Logger to log issuing requests caused by extensions on pages.

BUG=388287

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177761

Review URL: https://codereview.chromium.org/370763002

git-svn-id: svn://svn.chromium.org/blink/trunk@177845 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Use Reflect on attributes in xml namespace

Use Reflect on attributes in xml namespace, in order make this work teach v8_attributes.py about XMLNames namespace.

Review URL: https://codereview.chromium.org/378343004

git-svn-id: svn://svn.chromium.org/blink/trunk@177847 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Unflake inspector/sources/debugger/async-callstack-in-console.html

BUG=392531
TBR=yurys
NOTRY=true

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177807

Review URL: https://codereview.chromium.org/378293006

git-svn-id: svn://svn.chromium.org/blink/trunk@177848 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Move PrintContext to oilpan's heap

This CL replaces HashMap<String, Element*> with HeapHashMap<String, Member<Element>>.

BUG=340522

Review URL: https://codereview.chromium.org/382743003

git-svn-id: svn://svn.chromium.org/blink/trunk@177849 bbb929c8-8fbe-4397-9dbb-9b2b20218538