Bug 1525857 - Add release asserts for pre-crash cases. r=lsalzman

Differential Revision: https://phabricator.services.mozilla.com/D21145

--HG--
extra : moz-landing-system : lando

dom/canvas/WebGLProgram.cpp

@@ -473,6 +473,8 @@ static RefPtr<const webgl::LinkedProgramInfo> QueryProgramInfo(
 
   {
     const auto& fragShader = prog->FragShader();
+    MOZ_RELEASE_ASSERT(fragShader);
+    MOZ_RELEASE_ASSERT(fragShader->Validator());
     const auto& handle = fragShader->Validator()->Handle();
     const auto version = sh::GetShaderVersion(handle);
 

dom/canvas/WebGLShaderValidator.cpp

@@ -213,6 +213,7 @@ namespace webgl {
     const ShBuiltInResources& resources, ShCompileOptions compileOptions) {
   ShHandle handle =
       sh::ConstructCompiler(shaderType, spec, outputLanguage, &resources);
+  MOZ_RELEASE_ASSERT(handle);
   if (!handle) return nullptr;
 
   return new ShaderValidator(handle, compileOptions,