Eliminate dependencies on assemblers and code stubs in precompiled runtime.

runtime/vm/runtime_entry.cc

Index: runtime/vm/runtime_entry.cc
diff --git a/runtime/vm/runtime_entry.cc b/runtime/vm/runtime_entry.cc
index 3504e78830f6893a95ed14df30445eecf325dced..887cb7e9c9ac934d17ab47500eed0bd048dd6eed 100644
--- a/runtime/vm/runtime_entry.cc
+++ b/runtime/vm/runtime_entry.cc
@@ -2341,6 +2341,14 @@ DEFINE_RUNTIME_ENTRY(InitStaticField, 1) {
   field.EvaluateInitializer();
 }
 
+
+// Print the stop message.
+DEFINE_LEAF_RUNTIME_ENTRY(void, PrintStopMessage, 1, const char* message) {
+  OS::Print("Stop message: %s\n", message);
+}
+END_LEAF_RUNTIME_ENTRY
+
+
 // Use expected function signatures to help MSVC compiler resolve overloading.
 typedef double (*UnaryMathCFunction)(double x);
 typedef double (*BinaryMathCFunction)(double x, double y);