Revert "Reland "Implement statements and expressions in DSL C++ code generator.""

This reverts commit c412688798e572ac8ca6414a19a48d007500f751.

Reason for revert: fix Google3 roll and wasm build

Original change's description:
> Reland "Implement statements and expressions in DSL C++ code generator."
>
> This is a reland of 16cbfb41dff107ca3388bacf34201311d3c5f14d
>
> Tests now rely on `shaderDerivativeSupport` and `integerSupport` as
> proxies to indicate ES3 support. The SwitchStatement test has been
> adjusted to hopefully confuse fewer compilers.
>
> Original change's description:
> > Implement statements and expressions in DSL C++ code generator.
> >
> > This CL removes the bulk of the existing C++ code generator, especially
> > all the complex format-string assembly code. It has been replaced with
> > actual DSL code generation. Simple IR can now be successfully translated
> > to a working DSL fragment processor.
> >
> > This CL also adds a simple test harness which is patterned after the
> > existing SkSLTest; it renders a pixel, reads it back, and fails the test
> > if the result isn't solid green (RGBA=0101).
> >
> > This CL doesn't implement every feature. Some obvious gaps include:
> > - Sampling from children
> > - Uniforms/inputs of any kind
> > - Function calls of any kind
> >
> > Change-Id: Ib80c23fe1ba4453f7c3cb43b65f93c5ea0deb709
> > Bug: skia:11854
> > Reviewed-on: https://skia-review.googlesource.com/c/skia/+/396757
> > Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
> > Reviewed-by: Brian Osman <brianosman@google.com>
> > Commit-Queue: John Stiles <johnstiles@google.com>
>
> Bug: skia:11854, skia:11891
> Change-Id: I91363e31f34611d15ae350b52d6fc459feeace9c
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/399076
> Auto-Submit: John Stiles <johnstiles@google.com>
> Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
> Reviewed-by: Ethan Nicholas <ethannicholas@google.com>

TBR=brianosman@google.com,ethannicholas@google.com,johnstiles@google.com

Change-Id: I71a8cf31e8a013b7a2a0d10f0ad3bc3893ea07ea
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:11854
Bug: skia:11891
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/399499
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
39 files changed