Fix creating substring in string.replace(<global regexp>, <function>).

Fix creating substring in string.replace(<global regexp>, <function>).


BUG=
TEST=regexp-global.js

Committed: https://code.google.com/p/v8/source/detail?r=11661

[Yang, 2012-05-25 08:18:06]

PTAL.

This caused an assertion failure in debug mode when the subcapture is not an
actual substring.

[Erik Corry, 2012-05-25 10:50:07]

LGTM

[Lasse Reichstein Nielsen, 2012-05-29 09:06:52]

drive-by-comment

https://chromiumcodereview.appspot.com/10454032/diff/1/src/runtime.cc
File src/runtime.cc (right):

https://chromiumcodereview.appspot.com/10454032/diff/1/src/runtime.cc#newcode...
src/runtime.cc:3950: if (!first) {
"first" is actually badly named. It should be "atStart".

https://chromiumcodereview.appspot.com/10454032/diff/1/src/runtime.cc#newcode...
src/runtime.cc:3966: if (!first) {
Perhaps drop "first" and just check if start > 0 here.
Or, alternatively, just call NewSubString every time. I bet it starts checking
whether  start == 0  anyway, so removing the test here makes up for that.

https://chromiumcodereview.appspot.com/10454032/diff/1/test/mjsunit/regexp-gl...
File test/mjsunit/regexp-global.js (right):

https://chromiumcodereview.appspot.com/10454032/diff/1/test/mjsunit/regexp-gl...
test/mjsunit/regexp-global.js:129: // Test capture that is a real substring.
Description isn't very descriptive :)
You are testing that a regexp that matches the empty string will match once at
the end of the string?

https://chromiumcodereview.appspot.com/10454032/diff/1/test/mjsunit/regexp-gl...
test/mjsunit/regexp-global.js:132: assertEquals("~~");
Shouldn't there be a second argument here, probably str?
If this doesn't fail, is there a bug in assertEquals?

[Lasse Reichstein Nielsen, 2012-05-29 10:41:28]

https://chromiumcodereview.appspot.com/10454032/diff/1/test/mjsunit/regexp-gl...
File test/mjsunit/regexp-global.js (right):

https://chromiumcodereview.appspot.com/10454032/diff/1/test/mjsunit/regexp-gl...
test/mjsunit/regexp-global.js:129: // Test capture that is a real substring.
Actually, you are testing a capture that *isn't* a proper substring.

https://chromiumcodereview.appspot.com/10454032/diff/1/test/mjsunit/regexp-gl...
test/mjsunit/regexp-global.js:132: assertEquals("~~");
My bad, you already fixed that.