Revert "Add support for generic function type syntax, part 1" (TBR)

pkg/analyzer/lib/src/summary/summarize_const_expr.dart

Index: pkg/analyzer/lib/src/summary/summarize_const_expr.dart
diff --git a/pkg/analyzer/lib/src/summary/summarize_const_expr.dart b/pkg/analyzer/lib/src/summary/summarize_const_expr.dart
index e3a901766c474914854289f739c737cd7ff330aa..5a8702a99f7bad5baff07d16c9872b82015351e2 100644
--- a/pkg/analyzer/lib/src/summary/summarize_const_expr.dart
+++ b/pkg/analyzer/lib/src/summary/summarize_const_expr.dart
@@ -178,12 +178,8 @@ abstract class AbstractConstExprSerializer {
   /**
    * Return [EntityRefBuilder] that corresponds to the given [type].
    */
-  EntityRefBuilder serializeTypeName(TypeAnnotation type) {
-    if (type is TypeName) {
-      return serializeType(type?.type, type?.name, type?.typeArguments);
-    }
-    throw new ArgumentError(
-        'Cannot serialize an instance of ${type.runtimeType}');
+  EntityRefBuilder serializeTypeName(TypeName type) {
+    return serializeType(type?.type, type?.name, type?.typeArguments);
   }
 
   /**
@@ -653,8 +649,8 @@ abstract class AbstractConstExprSerializer {
       ints.add(0);
     } else {
       ints.add(typeArguments.arguments.length);
-      for (TypeAnnotation type in typeArguments.arguments) {
-        references.add(serializeTypeName(type));
+      for (TypeName typeName in typeArguments.arguments) {
+        references.add(serializeTypeName(typeName));
       }
     }
   }