Registering a new Symbol with the NameFor() of the source symbol creates
a new *named* symbol. When mixing these with unnamed symbols we can have
collisions.
Update CloneContext::Clone(Symbol) to properly clone unnamed symbols.
Update (most) the transforms to ctx.Clone() the symbols instead of
registering the names directly.
Fix up the tests where the symbol IDs have changed.
Note: We can still have symbol collisions if a program is authored with
identifiers like 'tint_symbol_3'. This will be fixed up in a later
change.
Change-Id: I0ce559644da3d60e1060f2eef185fa55ae284521
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/46866
Commit-Queue: Ben Clayton <bclayton@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: James Price <jrprice@google.com>
1b8d9f227b