Add ability to look up type parameters that are associated with ClassEntities with the element envi…

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 aa98d034e98a3bd413c54c9f4807010fb7e90df3..78ed5d2f458cd623eeb7bd19af7143c40c76a9fd 100644
--- a/pkg/compiler/lib/src/common_elements.dart
+++ b/pkg/compiler/lib/src/common_elements.dart
@@ -1348,6 +1348,15 @@ abstract class ElementEnvironment {
   /// Returns the type of the [local] function.
   FunctionType getLocalFunctionType(Local local);
 
+  /// Returns the set of type parameters associated with a given class entity.
+  /// For example, for a class Foo, declared like this:
+  ///
+  ///     class Foo<A, B>{}
+  ///
+  /// getTypeVariables would return a list containing the [DartType]s
+  /// corresponding to A and B.
+  List<DartType> getTypeVariables(ClassEntity cls);

[Johnni Winther, 2017/09/04 06:59:56]

[getClassTypeVariables] is probably better since methods can also have type
variables.

[Emily Fortuna, 2017/09/05 17:13:31]

Done.

+
   /// Gets the constant value of [field], or `null` if [field] is non-const.
   ConstantExpression getFieldConstant(FieldEntity field);