Rename JumpToBuiltin to JumpToRuntime. Add comment to ResolveBuiltin.

src/x64/builtins-x64.cc

Index: src/x64/builtins-x64.cc
===================================================================
--- src/x64/builtins-x64.cc	(revision 2967)
+++ src/x64/builtins-x64.cc	(working copy)
@@ -41,10 +41,10 @@
   __ movq(Operand(kScratchRegister, 0), rdi);
 
   // The actual argument count has already been loaded into register
-  // rax, but JumpToBuiltin expects rax to contain the number of
+  // rax, but JumpToRuntime expects rax to contain the number of
   // arguments including the receiver.
   __ incq(rax);
-  __ JumpToBuiltin(ExternalReference(id), 1);
+  __ JumpToRuntime(ExternalReference(id), 1);
 }