String equality improvements.

Added string equality by reading int-sized blocks of characters for
flat strings with the same representation.

[Erik Corry, 2008-10-20 09:40:04]

http://codereview.chromium.org/7518/diff/202/9
File src/objects.cc (right):

http://codereview.chromium.org/7518/diff/202/9#newcode3662
Line 3662: for (i = 0; i <= endpoint; i += kStepSize) {
If length = 3 then endpoint = 1, so we get into this loop once and compare 4
bytes, but only 3 are significant!

[Christian Plesner Hansen, 2008-10-20 09:52:09]

http://codereview.chromium.org/7518/diff/202/9
File src/objects.cc (right):

http://codereview.chromium.org/7518/diff/202/9#newcode3662
Line 3662: for (i = 0; i <= endpoint; i += kStepSize) {
If sizeof(Char) is 2 then endpoint is indeed 1 but then a string of length 3 has
6 significant bytes, not 3.  Alternatively, if sizeof(Char) is 1 then endpoint
is -1 and we skip block reading altogether.

[bak, 2008-10-20 10:50:42]

LGTM,
  Lars

http://codereview.chromium.org/7518/diff/202/9
File src/objects.cc (right):

http://codereview.chromium.org/7518/diff/202/9#newcode3652
Line 3652: static inline bool CompareRawStringContents(Vector<Char> a,
Vector<Char> b) {
How about an assert checking a.length() == b.length()?

http://codereview.chromium.org/7518/diff/202/9#newcode3665
Line 3665: if (wa != wb)
Move return false to previous line or add {}.

http://codereview.chromium.org/7518/diff/202/9#newcode3669
Line 3669: for (; i < length; i++)
Missing {}