Remove RefPtrHashMap

Remove RefPtrHashMap

The recently added 'HashTraits::PeekInType' type allows us to remove
HashMap<RefPtr..> template specialization without loosing the efficiency
and without bringing any significant changes and complexity to the HashMap
class.

To get rid of 'RefPtrHashMap' a new 'RefPtrValuePeeker' type was created
and used as 'HashTraits::PeekInType' for RefPtr. The 'RefPtrValuePeeker'
class can be constructed either from RefPtr, PassRefPtr or a plain pointer,
then it behaves like a plain pointer itself within HashTable methods.

The proposed change brings the following benefits:
1) Removes tons of duplicated code
2) Allows avoiding ref-count churn also at HashSet<RefPtr>

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=168593

[Mikhail, 2014-03-05 14:59:03]

PTAL

[tkent, 2014-03-05 23:12:43]

lgtm

[commit-bot: I haz the power, 2014-03-05 23:13:20]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/mikhail.pozdnyakov@intel.com/184233006/1

[commit-bot: I haz the power, 2014-03-05 23:13:46]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-03-05 23:13:46]

Try jobs failed on following builders: linux_blink

[Mikhail, 2014-03-06 06:27:47]

The CQ bit was checked by mikhail.pozdnyakov@intel.com

[commit-bot: I haz the power, 2014-03-06 06:28:10]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/mikhail.pozdnyakov@intel.com/184233006/1

[commit-bot: I haz the power, 2014-03-06 08:08:35]

Change committed as 168593