Use entities in TypeVariableResolutionAnalysis and TypeVariableCodegenAnalysis

pkg/compiler/lib/src/common_elements.dart

Index: pkg/compiler/lib/src/common_elements.dart
diff --git a/pkg/compiler/lib/src/common_elements.dart b/pkg/compiler/lib/src/common_elements.dart
index 29a1a004e159508e5e0720b5a5f35944eb140f1e..ddc0761bea70e7acaf2ae7902ae57f6fb9d67717 100644
--- a/pkg/compiler/lib/src/common_elements.dart
+++ b/pkg/compiler/lib/src/common_elements.dart
@@ -285,6 +285,10 @@ abstract class ElementEnvironment {
   /// where the type arguments are the type variables of [cls].
   InterfaceType getThisType(ClassEntity cls);
 
+  /// The upper bound on the [typeVariable]. If not explicitly declared, this is
+  /// `Object`.
+  DartType getTypeVariableBound(TypeVariableEntity typeVariable);
+
   /// Returns `true` if [a] is a subtype of [b].
   bool isSubtype(DartType a, DartType b);