Revert "Revert "Removed SkSL SymbolTable aliases""

The previous land contained a stray reference to the now-absent
SkSLSymbolAlias.h in sksl.gni.

This reverts commit f5853ff6525b2ede5683f3c3433386df9712a400.

Change-Id: I911d99de3dd98bc91a3bbfd9a52634dd51a660f2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/491816
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
19 files changed