Add 'isBoolean' method to SkSL::Type.

We have built-in methods for determining whether a type is an int,
float, signed, unsigned, matrix, vector, etc. For some reason, however,
the lowly boolean never received similar treatment. Now, booleans are a
first-class citizen and can be identified by calling `isBoolean` instead
of doing a string compare or looking at the Context type pointers.

(I did do a quick search to make sure that kNonnumeric wasn't used
anywhere else to check for Boolean-ness.)

Change-Id: I35c0e3c7530c13e2c4e307a70272d298ce6b44bc
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/338042
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
5 files changed