Enables stack frame vm tests on MIPS.

runtime/vm/stack_frame_test.cc

Index: runtime/vm/stack_frame_test.cc
===================================================================
--- runtime/vm/stack_frame_test.cc	(revision 21897)
+++ runtime/vm/stack_frame_test.cc	(working copy)
@@ -16,11 +16,6 @@
 
 namespace dart {
 
-// Only ia32, x64, and arm can run stack frame iteration tests.
-#if defined(TARGET_ARCH_IA32) ||                                               \
-    defined(TARGET_ARCH_X64) ||                                                \
-    defined(TARGET_ARCH_ARM)
-
 // Unit test for empty stack frame iteration.
 TEST_CASE(EmptyStackFrameIteration) {
   StackFrameIterator iterator(StackFrameIterator::kValidateFrames);
@@ -290,6 +285,4 @@
   EXPECT_VALID(Dart_Invoke(cls, NewString("testMain"), 0, NULL));
 }
 
-#endif  // TARGET_ARCH_IA32 || TARGET_ARCH_X64 || TARGET_ARCH_ARM
-
 }  // namespace dart