[FastTextAutosizer] Fix footer autosizing on common sites.

This patch fixes a bug where footers were autosized incorrectly on many
common sites (e.g., 360.cn). The issue was that descendant clusters were
included in textLength, but they should not be.

With this patch we pass one additional test! I've also included a test
from 360.cn that failed before this patch.

BUG=302005

Review URL: https://codereview.chromium.org/176983002

git-svn-id: svn://svn.chromium.org/blink/trunk@167760 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Check for null handle in V8NodeFilterCondition

R=jochen@chromium.org

BUG=345486

Review URL: https://codereview.chromium.org/177073005

git-svn-id: svn://svn.chromium.org/blink/trunk@167761 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Inline FloatSize::FloatSize(WebCore::IntSize const&) constructor.

The 'FloatSize::FloatSize(WebCore::IntSize const&)' invoked
from 'WebCore:ScrollView::visibleContentRect()' is mentioned
as a hotspot by the Intel VTune Amplifier profiler when
running 'Bindings/scroll-top.html' performance test.

This patch drives 'FloatSize::FloatSize(WebCore::IntSize const&)'
out from hotspot list, the profiler shows the 17.266s - 16.892s = 0.374s CPU time
gain with the mentioned performance test (linux desktop x64,
GCC 4.6.3, release content_shell build with enabled 'linux_dump_symbols' and 'use_aura' flags).

The results of the test  itself shows approx. 2% improvement.

before:
avg 179.5117899549199 runs/s
median 179.34441817013072 runs/s
stdev 0.961589016681394 runs/s
min 177.50819073435397 runs/s
max 180.8325271219252 runs/s

after:
avg 182.7270546104547 runs/s
median 183.16105219039957 runs/s
stdev 1.6022086143321321 runs/s
min 178.72507742693386 runs/s
max 185.07648946767654 runs/s

Review URL: https://codereview.chromium.org/174163011

git-svn-id: svn://svn.chromium.org/blink/trunk@167762 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Change WorkerRunLoop::Task to look more similar to WebThread::Task

BUG=301514
R=kinuko@chromium.org

Review URL: https://codereview.chromium.org/179563002

git-svn-id: svn://svn.chromium.org/blink/trunk@167763 bbb929c8-8fbe-4397-9dbb-9b2b20218538