This CL starts adding the basics for an IR for Tint. The IR is
a lower level representation then the AST with several of the
restrictions removed. For example, the IR is mutable, is a DAG
instead of a tree, and removes a number of WGSL constructs to
simplify transforms.
Bug: tint:1718
Change-Id: I6a16ac3116cee31410896c3a0424af7b41f958c3
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/105800
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
eee8d88210