Add support for WGSL shaders via Tint

BUG=dawn:405

Change-Id: I7a79a0d7ce58ff995ec1ff917dd427875fb4deaf
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/21340
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Ryan Harrison <rharrison@chromium.org>

src/dawn_native/opengl/ShaderModuleGL.cpp

@@ -68,6 +68,7 @@ namespace dawn_native { namespace opengl {
     }
 
     MaybeError ShaderModule::Initialize() {
+        DAWN_TRY(InitializeBase());
         const std::vector<uint32_t>& spirv = GetSpirv();
 
         std::unique_ptr<spirv_cross::CompilerGLSL> compilerImpl;