More analyzer updates, and handle negative_tests

lib/src/codegen/side_effect_analysis.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/generated/constant.dart';
 import 'package:analyzer/src/generated/error.dart'
     show AnalysisErrorListener, ErrorReporter;
 import 'package:analyzer/src/generated/resolver.dart' show TypeProvider;
 import 'package:analyzer/src/generated/source.dart' show Source;
+import 'package:analyzer/src/dart/ast/ast.dart';
 
 /// True is the expression can be evaluated multiple times without causing
 /// code execution. This is true for final fields. This can be true for local
 /// variables, if:
 /// * they are not assigned within the [context].
 /// * they are not assigned in a function closure anywhere.
 /// True is the expression can be evaluated multiple times without causing
 /// code execution. This is true for final fields. This can be true for local
 /// variables, if:
 ///
@@ skipping 24 matching lines @@
       }
     }
   }
   return false;
 }
 
 /// Returns true if the local variable is potentially mutated within [context].
 /// This accounts for closures that may have been created outside of [context].
 bool _isPotentiallyMutated(FunctionBody function, VariableElement e,
     [AstNode context]) {
+  if (function is FunctionBodyImpl && function.localVariableInfo == null) {
+    // TODO(jmesserly): this is a caching bug in Analyzer. They don't restore
+    // this info in some cases.
+    return true;
+  }
+
   if (function.isPotentiallyMutatedInClosure(e)) return true;
   if (function.isPotentiallyMutatedInScope(e)) {
     // Need to visit the context looking for assignment to this local.
     if (context != null) {
       var visitor = new _AssignmentFinder(e);
       context.accept(visitor);
       return visitor._potentiallyMutated;
     }
     return true;
   }
@@ skipping 55 matching lines @@
     // ConstantEvaluator will not compute constants for non-const fields,
     // so run ConstantVisitor for those to figure out if the initializer is
     // actually a constant (and therefore side effect free to evaluate).
     assert(!field.isConst);
 
     var initializer = field.initializer;
     if (initializer == null) return null;
     return initializer.accept(_constantVisitor);
   }
 }