Fix inferMethodInvocation in the case where interfaceMember is null.

pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart

Index: pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
index d47684145b24c2f64a4905fab7531f62faed53f8..84ceb23eefefc33a9a408f54d582d2d890b3f8c9 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
@@ -1829,8 +1829,10 @@ class KernelSuperMethodInvocation extends SuperMethodInvocation
   @override
   DartType _inferExpression(
       KernelTypeInferrer inferrer, DartType typeContext, bool typeNeeded) {
-    inferrer.instrumentation?.record(Uri.parse(inferrer.uri), fileOffset,
-        'target', new InstrumentationValueForMember(interfaceTarget));
+    if (interfaceTarget != null) {
+      inferrer.instrumentation?.record(Uri.parse(inferrer.uri), fileOffset,
+          'target', new InstrumentationValueForMember(interfaceTarget));
+    }
     return inferrer.inferMethodInvocation(this, new KernelThisExpression(),
         fileOffset, false, typeContext, typeNeeded,
         interfaceMember: interfaceTarget,