Change some explicit type checks into using helper functions.

src/assembler_ia32.h

Index: src/assembler_ia32.h
diff --git a/src/assembler_ia32.h b/src/assembler_ia32.h
index 5066397e93d978f70912958cf89669861f7fc097..3e9a93741241b901044a8cc5ff8b465985a0d5d0 100644
--- a/src/assembler_ia32.h
+++ b/src/assembler_ia32.h
@@ -51,7 +51,7 @@ public:
         DisplacementRelocation(Kind, Sym);
   }
 
-  void Process(const MemoryRegion &region, intptr_t position) {
+  void Process(const MemoryRegion &region, intptr_t position) override {
     (void)region;
     (void)position;
     llvm_unreachable("We might not be using this Process() method later.");