GC_TRACING dumps its result to stderr

Before this patch, GC_TRACING dumped its result to stdout.
This has caused all LayoutTests to fail.

This patch changes dump output to stderr, so LayoutTest run is not affected.

Unfortunately there is no trybot with ENABLE(GC_TRACING).
NOTRY=true
BUG=381038

Review URL: https://codereview.chromium.org/314943004

git-svn-id: svn://svn.chromium.org/blink/trunk@175560 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/platform/heap/Heap.cpp

@@ -1338,7 +1338,7 @@ public:
         }
         ObjectGraph::AddResult result = objectGraph().add(reinterpret_cast<uintptr_t>(objectPointer), std::make_pair(reinterpret_cast<uintptr_t>(m_hostObject), m_hostName));
         ASSERT(result.isNewEntry);
-        // printf("%s[%p] -> %s[%p]\n", m_hostName.ascii().data(), m_hostObject, className.ascii().data(), objectPointer);
+        // fprintf(stderr, "%s[%p] -> %s[%p]\n", m_hostName.ascii().data(), m_hostObject, className.ascii().data(), objectPointer);
 #endif
         if (callback)
             Heap::pushTraceCallback(const_cast<void*>(objectPointer), callback);
@@ -1426,14 +1426,14 @@ public:
 #if ENABLE(GC_TRACING)
     void reportStats()
     {
-        printf("\n---------- AFTER MARKING -------------------\n");
+        fprintf(stderr, "\n---------- AFTER MARKING -------------------\n");
         for (LiveObjectMap::iterator it = currentlyLive().begin(), end = currentlyLive().end(); it != end; ++it) {
-            printf("%s %u", it->key.ascii().data(), it->value.size());
+            fprintf(stderr, "%s %u", it->key.ascii().data(), it->value.size());
 
             if (it->key == "WebCore::Document")
                 reportStillAlive(it->value, previouslyLive().get(it->key));
 
-            printf("\n");
+            fprintf(stderr, "\n");
         }
 
         previouslyLive().swap(currentlyLive());
@@ -1448,7 +1448,7 @@ public:
     {
         int count = 0;
 
-        printf(" [previously %u]", previous.size());
+        fprintf(stderr, " [previously %u]", previous.size());
         for (LiveObjectSet::iterator it = current.begin(), end = current.end(); it != end; ++it) {
             if (previous.find(*it) == previous.end())
                 continue;
@@ -1458,27 +1458,27 @@ public:
         if (!count)
             return;
 
-        printf(" {survived 2GCs %d: ", count);
+        fprintf(stderr, " {survived 2GCs %d: ", count);
         for (LiveObjectSet::iterator it = current.begin(), end = current.end(); it != end; ++it) {
             if (previous.find(*it) == previous.end())
                 continue;
-            printf("%ld", *it);
+            fprintf(stderr, "%ld", *it);
             if (--count)
-                printf(", ");
+                fprintf(stderr, ", ");
         }
         ASSERT(!count);
-        printf("}");
+        fprintf(stderr, "}");
     }
 
     static void dumpPathToObjectFromObjectGraph(const ObjectGraph& graph, uintptr_t target)
     {
-        printf("Path to %lx of %s\n", target, classOf(reinterpret_cast<const void*>(target)).ascii().data());
+        fprintf(stderr, "Path to %lx of %s\n", target, classOf(reinterpret_cast<const void*>(target)).ascii().data());
         ObjectGraph::const_iterator it = graph.find(target);
         while (it != graph.end()) {
-            printf("<- %lx of %s\n", it->value.first, it->value.second.ascii().data());
+            fprintf(stderr, "<- %lx of %s\n", it->value.first, it->value.second.ascii().data());
             it = graph.find(it->value.first);
         }
-        printf("\n");
+        fprintf(stderr, "\n");
     }
 
     static void dumpPathToObjectOnNextGC(void* p)