Addition to CodePatcher

runtime/vm/code_patcher_ia32.cc

Index: runtime/vm/code_patcher_ia32.cc
===================================================================
--- runtime/vm/code_patcher_ia32.cc	(revision 1620)
+++ runtime/vm/code_patcher_ia32.cc	(working copy)
@@ -24,12 +24,19 @@
  public:
   explicit DartCallPattern(uword return_address)
       : start_(return_address - (kNumInstructions * kInstructionSize)) {
-    ASSERT(*reinterpret_cast<uint8_t*>(start_) == 0xB9);
-    ASSERT(*reinterpret_cast<uint8_t*>(start_ + 1 * kInstructionSize) == 0xBA);
-    ASSERT(*reinterpret_cast<uint8_t*>(start_ + 2 * kInstructionSize) == 0xE8);
+    ASSERT(IsValid(return_address));
     ASSERT(kInstructionSize == Assembler::kCallExternalLabelSize);
   }
 
+  static bool IsValid(uword return_address) {
+    uint8_t* code_bytes =
+        reinterpret_cast<uint8_t*>(
+            return_address - (kNumInstructions * kInstructionSize));
+    return (code_bytes[0] == 0xB9) &&
+           (code_bytes[kInstructionSize] == 0xBA) &&
+           (code_bytes[2 * kInstructionSize] == 0xE8);
+  }
+
   uword target() const {
     const uword offset = *reinterpret_cast<uword*>(call_address() + 1);
     return return_address() + offset;
@@ -217,6 +224,11 @@
 }
 
 
+bool CodePatcher::IsDartCall(uword return_address) {
+  return DartCallPattern::IsValid(return_address);
+}
+
+
 void CodePatcher::GetInstanceCallAt(uword return_address,
                                     String* function_name,
                                     int* num_arguments,