Adds support for debugger API on MIPS.

runtime/vm/isolate_test.cc

Index: runtime/vm/isolate_test.cc
===================================================================
--- runtime/vm/isolate_test.cc	(revision 21950)
+++ runtime/vm/isolate_test.cc	(working copy)
@@ -18,10 +18,6 @@
 }
 
 
-#if defined(TARGET_ARCH_IA32) ||                                               \
-    defined(TARGET_ARCH_X64) ||                                                \
-    defined(TARGET_ARCH_ARM)
-
 // Test to ensure that an exception is thrown if no isolate creation
 // callback has been set by the embedder when an isolate is spawned.
 TEST_CASE(IsolateSpawn) {
@@ -44,6 +40,4 @@
   EXPECT_VALID(exception_result);
 }
 
-#endif  // TARGET_ARCH_IA32 || TARGET_ARCH_X64 || TARGET_ARCH_ARM
-
 }  // namespace dart