Report a static warning if a for loop condition is non-boolean.

pkg/analyzer/lib/src/generated/error_verifier.dart

 // Copyright (c) 2014, 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.
 
 library analyzer.src.generated.error_verifier;
 
 import 'dart:collection';
 import "dart:math" as math;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 664 matching lines @@
   Object visitFieldFormalParameter(FieldFormalParameter node) {
     _checkForValidField(node);
     _checkForConstFormalParameter(node);
     _checkForPrivateOptionalParameter(node);
     _checkForFieldInitializingFormalRedirectingConstructor(node);
     _checkForTypeAnnotationDeferredClass(node.type);
     return super.visitFieldFormalParameter(node);
   }
 
   @override
+  Object visitForStatement(ForStatement node) {
+    if (node.condition != null) {
+      _checkForNonBoolCondition(node.condition);
+    }
+    return super.visitForStatement(node);
+  }
+
+  @override
   Object visitFunctionDeclaration(FunctionDeclaration node) {
     ExecutableElement outerFunction = _enclosingFunction;
     try {
       SimpleIdentifier identifier = node.name;
       String methodName = "";
       if (identifier != null) {
         methodName = identifier.name;
       }
       _enclosingFunction = node.element;
       TypeName returnType = node.returnType;
@@ skipping 5512 matching lines @@
     toCheck.add(type.element);
     // type arguments
     if (type is InterfaceType) {
       InterfaceType interfaceType = type;
       for (DartType typeArgument in interfaceType.typeArguments) {
         _addTypeToCheck(typeArgument);
       }
     }
   }
 }