emit 'this.x' when 'super.x' accesses a field

lib/src/compiler/code_generator.dart

Index: lib/src/compiler/code_generator.dart
diff --git a/lib/src/compiler/code_generator.dart b/lib/src/compiler/code_generator.dart
index ca56b1f7938fadaa362d2916ea0bc13415cc0d81..199a629e74a9a4fbdc601c56b03680ae25dd8ca9 100644
--- a/lib/src/compiler/code_generator.dart
+++ b/lib/src/compiler/code_generator.dart
@@ -2963,7 +2963,7 @@ class CodeGenerator extends GeneralizingAstVisitor
     if (isLibraryPrefix(node.prefix)) {
       return _visit(node.identifier);
     } else {
-      return _emitGet(node.prefix, node.identifier);
+      return _emitAccess(node.prefix, node.identifier);
     }
   }
 
@@ -2972,7 +2972,7 @@ class CodeGenerator extends GeneralizingAstVisitor
     if (node.operator.lexeme == '?.') {
       return _emitNullSafe(node);
     }
-    return _emitGet(_getTarget(node), node.propertyName);
+    return _emitAccess(_getTarget(node), node.propertyName);
   }
 
   JS.Expression _emitNullSafe(Expression node) {
@@ -3042,7 +3042,7 @@ class CodeGenerator extends GeneralizingAstVisitor
   }
 
   /// Shared code for [PrefixedIdentifier] and [PropertyAccess].
-  JS.Expression _emitGet(Expression target, SimpleIdentifier memberId) {
+  JS.Expression _emitAccess(Expression target, SimpleIdentifier memberId) {
     var member = memberId.staticElement;
     if (member is PropertyAccessorElement) {
       member = (member as PropertyAccessorElement).variable;
@@ -3054,6 +3054,14 @@ class CodeGenerator extends GeneralizingAstVisitor
       return js.call('dart.dload(#, #)', [_visit(target), name]);
     }
 
+    if (target is SuperExpression &&
+        member is FieldElement &&
+        !member.isSynthetic) {
+      // If super.x is actually a field, then x is an instance property since
+      // subclasses cannot override x.
+      return js.call('this.#', [name]);
+    }
+
     String code;
     if (member != null && member is MethodElement && !isStatic) {
       // Tear-off methods: explicitly bind it.