Convert String and List to abstract classes.

runtime/vm/flow_graph_compiler_ia32.cc

Index: runtime/vm/flow_graph_compiler_ia32.cc
diff --git a/runtime/vm/flow_graph_compiler_ia32.cc b/runtime/vm/flow_graph_compiler_ia32.cc
index f785ba93880a0a8d1a567a8a4ba2d28dc9a495d8..51cdb794ab7b81d938cf1afae63b94433313c576 100644
--- a/runtime/vm/flow_graph_compiler_ia32.cc
+++ b/runtime/vm/flow_graph_compiler_ia32.cc
@@ -148,7 +148,7 @@ FlowGraphCompiler::GenerateInstantiatedTypeWithArgumentsTest(
       __ cmpl(kClassIdReg, Immediate(type_class.id()));
       __ j(EQUAL, is_instance_lbl);
     }
-    if (type.IsListInterface()) {
+    if (type.IsListType()) {
       GenerateListTypeCheck(kClassIdReg, is_instance_lbl);
     }
     return GenerateSubtype1TestCacheLookup(
@@ -257,7 +257,7 @@ bool FlowGraphCompiler::GenerateInstantiatedTypeNoArgumentsTest(
         kClassIdReg, type, is_instance_lbl, is_not_instance_lbl);
     return false;
   }
-  if (type.IsStringInterface()) {
+  if (type.IsStringType()) {
     GenerateStringTypeCheck(kClassIdReg, is_instance_lbl, is_not_instance_lbl);
     return false;
   }