Remove unnecessary work from VariablePacker The VariablePacker does not check the staticUse flag, variables should be pre-filtered according to their staticUse flag before passing them to CheckVariablesInPackingLimits if that's desired. The names of the variables are also not relevant to the packing. We keep the "name" field to make the code easier to debug, but updating the mappedName is not useful. This will make implementing arrays of arrays simpler. BUG=angleproject:2125 TEST=angle_unittests Change-Id: I5ce91885f6478ad436e6fa60ca9675e161d10256 Reviewed-on: https://chromium-review.googlesource.com/730104 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>