Always send the current URL/title to the activity log when logging

When calling into WebDOMActivityLogger::log, the current location and
title for the page should always be passed in--otherwise, when a
WebDOMActivityLogger is re-used across multiple pages stale data can be
logged.

This is the first in a sequence of changes, and defines and calls a new
logging API in the blink tree.  Actual logging will still go through the
old path until the corresponding new method is added in the Chrome tree.

BUG=294500

Review URL: https://chromiumcodereview.appspot.com/23817008

git-svn-id: svn://svn.chromium.org/blink/trunk@158128 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Gardening, mark fast/html/imports/import-in-iframe.html as flaky

BUG=295789
TBR=

Review URL: https://codereview.chromium.org/23566021

git-svn-id: svn://svn.chromium.org/blink/trunk@158129 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Exit early in HashTable destructor if it is empty.

It is common for a HashTable to never get used. By adding an early exit, we
avoid an expensive function call to deallocateTable(). Even if that were to get
inlined, the expensive call to fastFree(NULL) cannot be avoided.

Review URL: https://chromiumcodereview.appspot.com/23929004

git-svn-id: svn://svn.chromium.org/blink/trunk@158130 bbb929c8-8fbe-4397-9dbb-9b2b20218538