Port a couple more stubs to x64.

runtime/vm/cpu_arm.cc

Index: runtime/vm/cpu_arm.cc
===================================================================
--- runtime/vm/cpu_arm.cc	(revision 3170)
+++ runtime/vm/cpu_arm.cc	(working copy)
@@ -31,9 +31,9 @@
 }
 
 
-void CPU::JumpToExceptionHandler(uword pc,
-                                 uword sp,
-                                 uword fp,
+void CPU::JumpToExceptionHandler(uword program_counter,
+                                 uword stack_pointer,
+                                 uword frame_pointer,
                                  const Instance& exception_object,
                                  const Instance& stacktrace_object) {
   UNIMPLEMENTED();
@@ -41,9 +41,9 @@
 
 
 void CPU::JumpToUnhandledExceptionHandler(
-    uword pc,
-    uword sp,
-    uword fp,
+    uword program_counter,
+    uword stack_pointer,
+    uword frame_pointer,
     const UnhandledException& unhandled_exception) {
   UNIMPLEMENTED();
 }