Verify that constant vectors aren't invalidated during iteration.

third_party/WebKit/Source/core/css/MediaQueryEvaluator.cpp

 /*
  * CSS Media Query Evaluator
  *
  * Copyright (C) 2006 Kimmo Kinnunen <kimmo.t.kinnunen@nokia.com>.
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ skipping 133 matching lines @@
     MediaQueryResultList* deviceDependentMediaQueryResults) const {
   if (!querySet)
     return true;
 
   const HeapVector<Member<MediaQuery>>& queries = querySet->queryVector();
   if (!queries.size())
     return true;  // Empty query list evaluates to true.
 
   // Iterate over queries, stop if any of them eval to true (OR semantics).
   bool result = false;
-  for (size_t i = 0; i < queries.size() && !result; ++i)
+  for (size_t i = 0; i < queries.size() && !result; ++i) {
+    // TODO(sof): CHECK() added for crbug.com/699269 diagnosis, remove sooner.
+    CHECK_EQ(queries.data(), querySet->queryVector().data());
     result = eval(queries[i].get(), viewportDependentMediaQueryResults,
                   deviceDependentMediaQueryResults);
+  }
 
   return result;
 }
 
 template <typename T>
 bool compareValue(T a, T b, MediaFeaturePrefix op) {
   switch (op) {
     case MinPrefix:
       return a >= b;
     case MaxPrefix:
@@ skipping 643 matching lines @@
   // Call the media feature evaluation function. Assume no prefix and let
   // trampoline functions override the prefix if prefix is used.
   EvalFunc func = gFunctionMap->at(expr->mediaFeature().impl());
   if (func)
     return func(expr->expValue(), NoPrefix, *m_mediaValues);
 
   return false;
 }
 
 }  // namespace blink