Update invariant for unresolved (static) get.

pkg/compiler/lib/src/ssa/builder.dart

Index: pkg/compiler/lib/src/ssa/builder.dart
diff --git a/pkg/compiler/lib/src/ssa/builder.dart b/pkg/compiler/lib/src/ssa/builder.dart
index 24e1ffb4773cb693a96c4e8868bcc6a62973c1ba..b68486ad966df80d409257c71b5fe23371c33605 100644
--- a/pkg/compiler/lib/src/ssa/builder.dart
+++ b/pkg/compiler/lib/src/ssa/builder.dart
@@ -3298,7 +3298,7 @@ class SsaBuilder extends NewResolvedVisitor {
           argumentNodes: const Link<ast.Node>());
     } else {
       // This happens when [element] has parse errors.
-      assert(invariant(node, element.isErroneous));
+      assert(invariant(node, element == null || element.isErroneous));
       // TODO(ahe): Do something like the above, that is, emit a runtime
       // error.
       stack.add(graph.addConstantNull(compiler));