Store the RegExp and the string specialization cid in an Array in RawFunction::data_.

runtime/vm/flow_graph_type_propagator.cc

Index: runtime/vm/flow_graph_type_propagator.cc
diff --git a/runtime/vm/flow_graph_type_propagator.cc b/runtime/vm/flow_graph_type_propagator.cc
index f0ac5a6a530f8d27b4b085cf4758efb9dbc6e461..6af05d6c52e0dc1a37c13f6253b84aa317718455 100644
--- a/runtime/vm/flow_graph_type_propagator.cc
+++ b/runtime/vm/flow_graph_type_propagator.cc
@@ -754,7 +754,7 @@ CompileType ParameterInstr::ComputeType() const {
     // from being generated.
     switch (index()) {
       case RegExpMacroAssembler::kParamStringIndex:
-        return CompileType::FromCid(function.regexp_cid());
+        return CompileType::FromCid(function.string_specialization_cid());
       case RegExpMacroAssembler::kParamStartOffsetIndex:
         return CompileType::FromCid(kSmiCid);
       default: UNREACHABLE();