* ProgramBuilder: added a bunch of overloads that take Source
* Added MultiTokenSource RAII helper to build source ranges for
multi-token types
* Added comparison operators to Source::Range and Source::Location to
make it easier to write tests to compare Source ranges
* Moved CombineSourceRange from resolver.cc to a static function in
Source named Source::Combine()
* Added Source tests for all ast type nodes returned by the wgsl parser
Bug: tint:724
Change-Id: I6fb6211a3c42c14693df8746af6a30f5aa56f2af
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/48963
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>