Use a pointer type for values in DocumentOrderedMap

Use a pointer type for values in DocumentOrderedMap (OwnPtr<MapEntry>) instead
of a struct type (MapEntry). This should hopefully fix the performance
regression on Bindings/get-element-by-id micro benchmark caused by r164029 on
some platforms.

While this CL seems to have no performance impact on Linux Desktop, I see a 14%
improvement on Bindings/get-element-by-id micro benchmark on Android (tested on
Galaxy Note 3 device). This may be due to HashTable optimizations when the
empty value for ValueType is zero, or to better caching.

R=esprehn, abarth
BUG=330778

Review URL: https://codereview.chromium.org/123333003

git-svn-id: svn://svn.chromium.org/blink/trunk@164440 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Don't use Color::m_valid for indicating color parsing success

This patch changes the Color constructors taking String into a setter
setFromString, which returns whether the String was correctly parsed.
The motivation here is to stop using invalid colors for a whole variety
of purposes, with an end goal of removing the bool from Color and having
a separate class StyleColor with a bool m_isCurrentColor.

TBR=abarth@chromium.org
BUG=331126

Review URL: https://codereview.chromium.org/122713002

git-svn-id: svn://svn.chromium.org/blink/trunk@164441 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add a release assert in Element's constructor to track down a crasher

R=abarth@chromium.org
BUG=312410

Review URL: https://codereview.chromium.org/102993010

git-svn-id: svn://svn.chromium.org/blink/trunk@164442 bbb929c8-8fbe-4397-9dbb-9b2b20218538