Always make a copy of a string when adding it to StringsStorage

Always make a copy of a string when adding it to StringsStorage

Otherwise the string passed as const char* may be disposed and we will end up with a dangling pointer.

Also changed StringsStorage::GetCopy so that a copy is not created if the string is already in the cache.

BUG=None
R=alph@chromium.org, svenpanne@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=17260

[yurys, 2013-10-17 11:46:48]

There is at least one case when the string stored in the storage will be
destroyed very soon after:
https://code.google.com/p/chromium/codesearch#chromium/src/v8/src/code-stubs....

[alph, 2013-10-17 12:19:09]

lgtm

https://codereview.chromium.org/27627006/diff/1/src/profile-generator.cc
File src/profile-generator.cc (right):

https://codereview.chromium.org/27627006/diff/1/src/profile-generator.cc#newc...
src/profile-generator.cc:47: 
nit: add extra lines around the function.

[yurys, 2013-10-17 12:56:41]

https://codereview.chromium.org/27627006/diff/1/src/profile-generator.cc
File src/profile-generator.cc (right):

https://codereview.chromium.org/27627006/diff/1/src/profile-generator.cc#newc...
src/profile-generator.cc:47: 
On 2013/10/17 12:19:09, alph wrote:
> nit: add extra lines around the function.

Done.

[yurys, 2013-10-18 08:07:47]

@svenpanne: need OWNER's approval

[Sven Panne, 2013-10-18 08:38:53]

LGTM (rubber-stamped)

[yurys, 2013-10-18 08:56:23]

Committed patchset #2 manually as r17260 (presubmit successful).