This reverts commit c14348a2.

Reason for revert: crashes in murmurhash on Nexus 6
See https://build.chromium.org/p/chromium.gpu.fyi/builders/Android%20Release%20%28Nexus%206%29/builds/7865

Original change's description:
> Adds TUnorderedMap and uses it for tLevel in TSymbolTableLevel.
> 
> Change-Id: I27ba7a41c599ef6f7fe68b22c27bd2a40175ddf9
> Reviewed-on: https://chromium-review.googlesource.com/526672
> Commit-Queue: Jamie Madill <jmadill@chromium.org>
> Reviewed-by: Jamie Madill <jmadill@chromium.org>

TBR=jmadill@chromium.org,kbr@chromium.org,bajones@chromium.org,kainino@chromium.org,lethalantidote@chromium.org

Change-Id: Id4a428430c6d286b910790ba7c30503c98ce728f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/551235Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>