Fixes to mock SDK to enable dart:core to be summarized.

pkg/analyzer/lib/src/generated/testing/element_factory.dart

Index: pkg/analyzer/lib/src/generated/testing/element_factory.dart
diff --git a/pkg/analyzer/lib/src/generated/testing/element_factory.dart b/pkg/analyzer/lib/src/generated/testing/element_factory.dart
index 3d1731b9694c539df6f592ee003b1dda3e1644ea..a092564630fc28fb0db117c98c8323e9994f4e4c 100644
--- a/pkg/analyzer/lib/src/generated/testing/element_factory.dart
+++ b/pkg/analyzer/lib/src/generated/testing/element_factory.dart
@@ -401,8 +401,10 @@ class ElementFactory {
     field.static = isStatic;
     field.synthetic = true;
     field.type = type;
+    field.final2 = true;
     PropertyAccessorElementImpl getter =
         new PropertyAccessorElementImpl.forVariable(field);
+    getter.synthetic = false;
     getter.getter = true;
     getter.variable = field;
     getter.returnType = type;