Bug 1120126 - Fix crash in RtlVirtualUnwind when starting the Gecko profiler on Win64. r=dmajor.

--HG--
extra : rebase_source : 46ed1ff91abf681d816a267f9496e0154b3d3542

tools/profiler/platform-win32.cc

@@ -189,7 +189,13 @@ class SamplerThread : public Thread {
     if (SuspendThread(profiled_thread) == kSuspendFailed)
       return;
 
+    // CONTEXT_CONTROL is faster but we can't use it on 64-bit because it
+    // causes crashes in RtlVirtualUnwind (see bug 1120126).
+#if V8_HOST_ARCH_X64
+    context.ContextFlags = CONTEXT_FULL;
+#else
     context.ContextFlags = CONTEXT_CONTROL;
+#endif
     if (GetThreadContext(profiled_thread, &context) != 0) {
 #if V8_HOST_ARCH_X64
       sample->pc = reinterpret_cast<Address>(context.Rip);