Emit switchable instance calls when we don't know the complete set of receiver classes for a call s…

runtime/vm/flow_graph_compiler_dbc.cc

Index: runtime/vm/flow_graph_compiler_dbc.cc
diff --git a/runtime/vm/flow_graph_compiler_dbc.cc b/runtime/vm/flow_graph_compiler_dbc.cc
index 69dd8ad56a4dbb769baa300748b7720b95c94d86..2b1763eaa1e370191cd0070c6fb8bcef9ad73c13 100644
--- a/runtime/vm/flow_graph_compiler_dbc.cc
+++ b/runtime/vm/flow_graph_compiler_dbc.cc
@@ -29,11 +29,6 @@ DEFINE_FLAG(bool, unbox_doubles, true, "Optimize double arithmetic.");
 DECLARE_FLAG(bool, enable_simd_inline);
 DECLARE_FLAG(charp, optimization_filter);
 
-void MegamorphicSlowPath::EmitNativeCode(FlowGraphCompiler* compiler) {
-  UNIMPLEMENTED();
-}
-
-
 FlowGraphCompiler::~FlowGraphCompiler() {
   // BlockInfos are zone-allocated, so their destructors are not called.
   // Verify the labels explicitly here.