Handle signature types and fields in kernel_impact

pkg/compiler/lib/src/universe/feature.dart

 // TODO(sigmund): rename universe => world
 /// Describes individual features that may be seen in a program. Most features
 /// can be described only by name using the [Feature] enum, some features are
 /// expressed including details on how they are used. For example, whether a
 /// list literal was constant or empty.
 ///
 /// The use of these features is typically discovered in an early phase of the
 /// compilation pipeline, for example during resolution.
 library compiler.universe.feature;
 
@@ skipping 22 matching lines @@
 
   /// A catch statement.
   CATCH_STATEMENT,
 
   /// A compile time error.
   COMPILE_TIME_ERROR,
 
   /// A fall through in a switch case.
   FALL_THROUGH_ERROR,
 
+  /// A field without an initializer.
+  FIELD_WITHOUT_INITIALIZER,
+
   /// A ++/-- operation.
   INC_DEC_OPERATION,
 
   /// A field whose initialization is not a constant.
   LAZY_FIELD,
 
   /// A catch clause with a variable for the stack trace.
   STACK_TRACE_IN_CATCH,
 
   /// String interpolation.
@@ skipping 76 matching lines @@
     if (other is! ListLiteralUse) return false;
     return type == other.type &&
         isConstant == other.isConstant &&
         isEmpty == other.isEmpty;
   }
 
   String toString() {
     return 'ListLiteralUse($type,isConstant:$isConstant,isEmpty:$isEmpty)';
   }
 }