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

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

Index: pkg/analyzer/lib/src/generated/error_verifier.dart
diff --git a/pkg/analyzer/lib/src/generated/error_verifier.dart b/pkg/analyzer/lib/src/generated/error_verifier.dart
index 008e046a8e69585e92badd47cd65cfa95b1e4e7a..32b4d315e4cc37d44d3bea57b6665dd7a1428a8c 100644
--- a/pkg/analyzer/lib/src/generated/error_verifier.dart
+++ b/pkg/analyzer/lib/src/generated/error_verifier.dart
@@ -682,6 +682,14 @@ class ErrorVerifier extends RecursiveAstVisitor<Object> {
   }
 
   @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 {