Move resolving of natives to a late stage (during code emission). That eliminates unnecessary nativ…

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index 0422cf3062225d5d95e6afc8864364ea6deb5e3a..43bbcbafdf6989103e9953a9832403cccc626754 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -852,7 +852,6 @@ static bool CompileParsedFunctionHelper(CompilationPipeline* pipeline,
           THR_Print("%s\n", error.ToErrorCString());
         }
         done = true;
-        ASSERT(optimized);
       }
 
       // Clear the error if it was not a real error, but just a bailout.
@@ -1091,8 +1090,14 @@ static RawError* CompileFunctionHelper(CompilationPipeline* pipeline,
         }
         function.SetIsOptimizable(false);
         return Error::null();
+      } else {
+        // Encountered error.
+        Error& error = Error::Handle();
+        // We got an error during compilation.
+        error = isolate->object_store()->sticky_error();
+        isolate->object_store()->clear_sticky_error();
+        return error.raw();
       }
-      UNREACHABLE();
     }
 
     per_compile_timer.Stop();