This will enable compile-time initialization of built-in symbols as
well as reducing copying strings.
Most of the code that deals with names is changed to use
ImmutableString where it makes sense to avoid conversions.
The lexer/parser now allocate const char pointers into pool memory
instead of allocating TStrings. These are then converted to
ImmutableString upon entering TParseContext.
BUG=angleproject:2267
TEST=angle_unittests, angle_end2end_tests
Change-Id: I244d6271ea1ecf7150d4f89dfa388a7745a1150c
Reviewed-on: https://chromium-review.googlesource.com/881561
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
