This patch removes the MathMax call from String.prototype.includes
in order to improve performance. With some quick and dirty benchmarking,
(test case courtesy of the node folks) a sizable performance gain is visible:

d8> function testIndexOf() { var stringArray = [ 'hello', 'world', '123', 'abc' ]; return stringArray.some(function(val, idx, arr) { return val.indexOf('world') !== -1 })}
d8> function testIncludes() { var stringArray = [ 'hello', 'world', '123', 'abc' ]; return stringArray.some(function(val, idx, arr) { return val.includes('world') })}
d8> function testTime(fn) { var before = Date.now(); fn(); return Date.now() - before; }
d8> testTime(function() { for (var i = 0; i < 10000000; i++) { testIncludes() } })
2244
d8> testTime(function() { for (var i = 0; i < 10000000; i++) { testIndexOf() } })
2212

Compare that to before the test, when the performance difference was much larger:

d8> testTime(function() { for (var i = 0; i < 10000000; i++) { testIndexOf() } })
2223
d8> testTime(function() { for (var i = 0; i < 10000000; i++) { testIncludes() } })
2650

In my runs, performance of both functions drifts up and down, but running them in quick
succession back and forth shows a roughly consistent delta of about this magnitude.

String.prototype.includes is still slightly (maybe 5%) slower than String.prototype.indexOf,
but the effect is significantly reduced.

R=adamk
BUG=v8:3807
LOG=Y

Review URL: https://codereview.chromium.org/1231673008

Cr-Commit-Position: refs/heads/master@{#29665}