Fix Dartium by supporting external strings as well in Symbols::FromConcatAll

Fix Dartium by supporting external strings as well in Symbols::FromConcatAll

BUG=
R=asiva@google.com

Committed: https://github.com/dart-lang/sdk/commit/df29a93b0dfd947e9437c309f914b063da4b9b20

[srdjan, 2015-09-02 17:40:34]

srdjan@google.com changed reviewers:
+ asiva@google.com

[siva, 2015-09-02 18:06:44]

lgtm

https://codereview.chromium.org/1323063004/diff/40001/runtime/vm/symbols.cc
File runtime/vm/symbols.cc (right):

https://codereview.chromium.org/1323063004/diff/40001/runtime/vm/symbols.cc#n...
runtime/vm/symbols.cc:428: const String& str = strs[i];
ASSERT(str.IsOneByteString() || str.IsExternalOneByteString());

https://codereview.chromium.org/1323063004/diff/40001/runtime/vm/symbols.cc#n...
runtime/vm/symbols.cc:453: ExternalOneByteString::CharAddr(str, 0);
It might make sense to add a String::CharAddr(...) function as you use this
pattern in more than one place.

We already have a String::CharAt(...)

[srdjan, 2015-09-02 18:24:37]

https://codereview.chromium.org/1323063004/diff/40001/runtime/vm/symbols.cc
File runtime/vm/symbols.cc (right):

https://codereview.chromium.org/1323063004/diff/40001/runtime/vm/symbols.cc#n...
runtime/vm/symbols.cc:428: const String& str = strs[i];
On 2015/09/02 18:06:44, siva wrote:
> ASSERT(str.IsOneByteString() || str.IsExternalOneByteString());

Done.

https://codereview.chromium.org/1323063004/diff/40001/runtime/vm/symbols.cc#n...
runtime/vm/symbols.cc:453: ExternalOneByteString::CharAddr(str, 0);
On 2015/09/02 18:06:44, siva wrote:
> It might make sense to add a String::CharAddr(...) function as you use this
> pattern in more than one place.
> 
> We already have a String::CharAt(...)

String::CharAddr was removed because it caused confusion.

[srdjan, 2015-09-02 18:25:30]

Committed patchset #4 (id:60001) manually as
df29a93b0dfd947e9437c309f914b063da4b9b20 (presubmit successful).