Added workaround for window.scrollX compat.

window.scrollX/Y is not available in IE11. As far as specifications go, is currently only specified in draft (http://dev.w3.org/csswg/cssom-view/#refsCSSOM). Falling back to 
window.pageXOffset seems like a good workaround.

On a related note; my Emscriptified project runs on IE11 although performance is very poor (mostly due to Internet Explorer itself, I think). It's pretty finicky about the shaders, as they introduced an extra set of requirements. (inout/in/out keywords not supported, can't construct mat3 from mat4, etc).
implementation of libuuid
Added comments & assert to scrollX fix.

Added comments to fix as per @kripken's request.
Added an assert too (guarded by ASSERTIONS define)
Fixed undefined check.

Forgot I had to explicitly check the type of variable type to see if it's undefined.
Added crypto quality random number generators for Node.js and browser environment if available
clean extra arg of JSify
Update library_browser.js
[SDL] Fixing SDL_UnlockSurface in IE10/IE11.

Previously, just calling SDL_UnlockSurface in IE10/IE11 would throw an exception, since Emscripten assumed that the ImageData's `data` property was Uint8ClampedArray, which has a backing buffer.

IE10/IE11 still uses the deprecated CanvasPixelArray, which does not have a backing buffer property:
https://developer.mozilla.org/en-US/docs/Web/API/CanvasPixelArray

I've added an additional path to SDL_UnlockSurface for these browsers.
Merge pull request #1971 from jvilk/sdl_fixes

[SDL] Fixing SDL_UnlockSurface in IE10/IE11
convert test_sdl_canvas to btest
disable named globals test in fastcomp
fix benchmark suite bug where args got appended
[SDL] Actually fix SDL_UnlockSurface in IE10/IE11.

The previous revision did not copy over pixel data properly. This time, I have reverted the IE path to the code used in this method prior to the breaking change, and have tested it with JSMESS.
disable/update various browser tests for fastcomp
Merge pull request #1973 from jvilk/sdl_fix

[SDL] Actually fix SDL_UnlockSurface in IE10/IE11.
optimize main loop in SDL_UnlockSurface to avoid a branch
Merge pull request #1941 from onnoj/incoming

Added workaround for window.scrollX compat.
Merge pull request #1967 from coolwanglu/pr_clean

clean extra arg of JSify
specify (void) as the arguments in webgl_context_attributes test, to avoid confusion with varargs by clang
todo about async script tags