Fix dummy mode for retina displays.
Whitelist pref access.
Profile load(...) statements.
Update dummy rendering.
Add build.js optimization pass to fold identifiers of the form |XXX_....|.

This helps a lot in interpreter loops since table switches are not emitted for this case:

var OP_add = 0;
var OP_sub = 1;

switch (op) {
  case OP_add: ... break;
  case OP_sub: ... break;
}

This pass transforms the code above as follows:

var OP_add = 0;
var OP_sub = 1;

switch (op) {
  case 0: ... break;
  case 1: ... break;
}
Added more timing markers.
Preload UTF Strings using the JavaScript parser instead.
Doesn't really make to measure parsing time this way.
Don't replace identifiers in wrong places.
Make sure constants are not redefined.
Update jsshell URL.
Merge pull request #118 from mbebenita/master

Perf updates.