Move tint::transform::Robustness to a santizier transform

There's no good reason for this to be public.
Move it into the writers, and expose a 'disable_robustness' option to
turn it off. This can be expanded to hold more fine-grain control in the
future.

Change-Id: I6ea6e54a27b2ae0fbcba5fdf45539063045cc15a
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/122203
Commit-Queue: Ben Clayton <bclayton@google.com>
Kokoro: Ben Clayton <bclayton@google.com>
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Auto-Submit: Ben Clayton <bclayton@google.com>
Reviewed-by: Austin Eng <enga@chromium.org>

src/dawn/native/opengl/ShaderModuleGL.cpp

@@ -228,6 +228,9 @@ ResultOrError<GLuint> ShaderModule::CompileShader(const OpenGLFunctions& gl,
             tintOptions.version = tint::writer::glsl::Version(ToTintGLStandard(r.glVersionStandard),
                                                               r.glVersionMajor, r.glVersionMinor);
 
+            // TODO(crbug.com/dawn/1686): Robustness causes shader compilation failures.
+            tintOptions.disable_robustness = true;
+
             // When textures are accessed without a sampler (e.g., textureLoad()),
             // GetSamplerTextureUses() will return this sentinel value.
             BindingPoint placeholderBindingPoint{static_cast<uint32_t>(kMaxBindGroupsTyped), 0};