Render string sequences of more than 64k characters.

Source/core/rendering/InlineIterator.h

Index: Source/core/rendering/InlineIterator.h
diff --git a/Source/core/rendering/InlineIterator.h b/Source/core/rendering/InlineIterator.h
index c2d2f53047398d9439514682904c8b56c41a6c3c..127c0876b9326337cde07a6977632b33680a9f08 100644
--- a/Source/core/rendering/InlineIterator.h
+++ b/Source/core/rendering/InlineIterator.h
@@ -624,10 +624,20 @@ private:
 
 static void inline appendRunObjectIfNecessary(RenderObject* obj, unsigned start, unsigned end, InlineBidiResolver& resolver, AppendRunBehavior behavior, IsolateTracker& tracker)
 {
-    if (behavior == AppendingFakeRun)
-        tracker.addFakeRunIfNecessary(obj, start, end, resolver);
-    else
-        resolver.runs().addRun(createRun(start, end, obj, resolver));
+    bool addEmptyRun = (end == start);

[eae, 2015/01/15 20:07:07]

The general approach seems fine, I have a hard time wrapping my head around the
concept of addEmptyRun though. Could you either try to reorganize the code to
not need it or add a comment explaining what it is used for.

[Daniel Bratell, 2015/01/16 13:47:32]

There is code that calls this with start == end and expects a BidiRun to be
created. If I just had the loop there would be no BidiRun anymore for that case.
Those that do that create an empty BidiRun and then modify the positions. I
think it was used for trailing whitespace.

I will add some kind of comment.

+    while (end > start || addEmptyRun) {
+        const int limit = USHRT_MAX; // Use a small number in Debug to keep the code well tested?
+        unsigned limitedEnd = end;
+        if (end - start > limit)
+            limitedEnd = start + limit;
+        if (behavior == AppendingFakeRun)
+            tracker.addFakeRunIfNecessary(obj, start, limitedEnd, resolver);
+        else
+            resolver.runs().addRun(createRun(start, limitedEnd, obj, resolver));
+        if (addEmptyRun)
+            break;
+        start = limitedEnd;
+    }
 }
 
 static void adjustMidpointsAndAppendRunsForObjectIfNeeded(RenderObject* obj, unsigned start, unsigned end, InlineBidiResolver& resolver, AppendRunBehavior behavior, IsolateTracker& tracker)