Merged r17432, r17526, r17545, r17620, r17747 into 3.20 branch.

Merged r17432, r17526, r17545, r17620, r17747 into 3.20 branch.

Do not remove HAdd with zero if the other operand is a double.

Age ICs on context dispose notification.

Fix y-umlaut to uppercase.

Fix potential assertion failure in ConvertCase.

Fix duplicate check in DependentCode::Insert.

BUG=309723, v8:2984, 318454
R=yangguo@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=18325

[ulan, 2013-12-17 11:55:03]

PTAL: This is based on https://code.google.com/p/v8/source/detail?r=17971.

src/code-stubs-hydrogen.cc and src/compiler.cc did not apply cleanly.

[Yang, 2013-12-17 12:30:53]

On 2013/12/17 11:55:03, ulan wrote:
> PTAL: This is based on https://code.google.com/p/v8/source/detail?r=17971.
> 
> src/code-stubs-hydrogen.cc and src/compiler.cc did not apply cleanly.

LGTM.

[ulan, 2013-12-17 12:42:44]

Committed patchset #1 manually as r18325.