Improve String.repeat.

Improve String.repeat.

Adapted from patch contributed by Isiah Meadows <impinball@gmail.com>;.

R=jkummerow@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=24687

[Jakob Kummerow, 2014-10-15 14:01:51]

lgtm

[aandrey, 2014-10-15 17:54:43]

aandrey@chromium.org changed reviewers:
+ aandrey@chromium.org

[aandrey, 2014-10-15 17:54:43]

https://codereview.chromium.org/657863002/diff/1/src/harmony-string.js
File src/harmony-string.js (right):

https://codereview.chromium.org/657863002/diff/1/src/harmony-string.js#newcode30
src/harmony-string.js:30: s += s;
There will be extra unnecessary concatenation at the end. Maybe:

while (1) {
  if (n & 1) r += s;
  n >>= 1;
  if (!n) break;
  s += s;
}

[Yang, 2014-10-17 10:01:46]

Committed patchset #2 (id:20001) manually as 24687 (presubmit successful).