Migrate DDC to the new analysis driver.

pkg/dev_compiler/lib/src/compiler/nullable_type_inference.dart

Index: pkg/dev_compiler/lib/src/compiler/nullable_type_inference.dart
diff --git a/pkg/dev_compiler/lib/src/compiler/nullable_type_inference.dart b/pkg/dev_compiler/lib/src/compiler/nullable_type_inference.dart
index dbba17103ecbab2aa55ccc7736710580ac6de378..ce902d1c6cb5156e72af5091e24fd3fc40286b57 100644
--- a/pkg/dev_compiler/lib/src/compiler/nullable_type_inference.dart
+++ b/pkg/dev_compiler/lib/src/compiler/nullable_type_inference.dart
@@ -86,7 +86,7 @@ abstract class NullableTypeInference {
         PropertyInducingElement variable = element.variable;
         var isVirtual =
             variable is FieldElement && virtualFields.isVirtual(variable);
-        return isVirtual || (variable.computeConstantValue()?.isNull ?? true);
+        return isVirtual || (variable.constantValue?.isNull ?? true);
       }
 
       // Other types of identifiers are nullable (parameters, fields).
@@ -190,7 +190,7 @@ abstract class NullableTypeInference {
         }
       }
 
-      if (e?.name == 'identical' && identical(e.library, dartCoreLibrary)) {
+      if (e != null && e.name == 'identical' && e.library.isDartCore) {
         return false;
       }
     }