Disable Wasm trap handler in msan builds

In msan builds, V8 generates ARM code and runs it in a simulator. This means we
cannot support trap handlers in that configuration.

TBR=jam@chromium.org

Bug: chromium:824645
Change-Id: If0971148262297d5688efd559a1526295a869e07
Reviewed-on: https://chromium-review.googlesource.com/979033Reviewed-by: Dominic Battré <battre@chromium.org>
Commit-Queue: Dominic Battré <battre@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545869}

content/renderer/render_process_impl.cc

@@ -154,7 +154,10 @@ RenderProcessImpl::RenderProcessImpl(
                      "--harmony-array-prototype-values");
   SetV8FlagIfNotFeature(features::kArrayPrototypeValues,
                         "--no-harmony-array-prototype-values");
-#if defined(OS_LINUX) && defined(ARCH_CPU_X86_64) && !defined(OS_ANDROID)
+// Memory sanitizer compiles V8 to generate ARM code and run it in a simulator,
+// meaning we cannot support trap handlers there.
+#if defined(OS_LINUX) && defined(ARCH_CPU_X86_64) && !defined(OS_ANDROID) && \
+    !defined(MEMORY_SANITIZER)
   if (base::FeatureList::IsEnabled(features::kWebAssemblyTrapHandler)) {
     bool use_v8_signal_handler = false;
     base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();