Eliminate dependencies on assemblers and code stubs in precompiled runtime.

runtime/vm/runtime_entry_x64.cc

Index: runtime/vm/runtime_entry_x64.cc
diff --git a/runtime/vm/runtime_entry_x64.cc b/runtime/vm/runtime_entry_x64.cc
index 84026eceb46f8fd19d73bfe11e520bd0392af4e1..bc0d8f1a363271cfba28caa3eca634628f446427 100644
--- a/runtime/vm/runtime_entry_x64.cc
+++ b/runtime/vm/runtime_entry_x64.cc
@@ -20,6 +20,7 @@ uword RuntimeEntry::GetEntryPoint() const {
 }
 
 
+#if !defined(DART_PRECOMPILED_RUNTIME)
 // Generate code to call into the stub which will call the runtime
 // function. Input for the stub is as follows:
 //   RSP : points to the arguments and return value array.
@@ -39,6 +40,7 @@ void RuntimeEntry::Call(Assembler* assembler, intptr_t argument_count) const {
     __ CallToRuntime();
   }
 }
+#endif  // !defined(DART_PRECOMPILED_RUNTIME)
 
 }  // namespace dart