Use entities internally in MemberTypeInformation

pkg/compiler/lib/src/dump_info.dart

Index: pkg/compiler/lib/src/dump_info.dart
diff --git a/pkg/compiler/lib/src/dump_info.dart b/pkg/compiler/lib/src/dump_info.dart
index aee7db62c422361fb3c69b7f05c33b9a5d52f1fc..5a092f3dd50467e361b761d615959009e803519d 100644
--- a/pkg/compiler/lib/src/dump_info.dart
+++ b/pkg/compiler/lib/src/dump_info.dart
@@ -126,6 +126,7 @@ class ElementInfoCollector extends BaseElementVisitor<Info, dynamic> {
       compiler.globalInference.results.resultOfParameter(e);
 
   FieldInfo visitFieldElement(FieldElement element, _) {
+    if (!compiler.resolution.hasBeenResolved(element)) return null;

[Johnni Winther, 2017/07/04 13:46:24]

This would trigger a 'type has not been compute' failure on unresolved field,
trying to create the default FieldTypeInformation object.

[Siggi Cherem (dart-lang), 2017/07/05 21:04:14]

do you mean we are hitting this issue on programs with input errors?

[Johnni Winther, 2017/07/06 09:38:14]

No. The visiting just eagerly runs through all fields, regardless of whether
they are live or not.

     TypeMask inferredType = _resultOfMember(element).type;
     // If a field has an empty inferred type it is never used.
     if (inferredType == null || inferredType.isEmpty) return null;