Dispose temporary and not-cached Range in DOMSelection

third_party/WebKit/Source/core/editing/DOMSelection.cpp

Index: third_party/WebKit/Source/core/editing/DOMSelection.cpp
diff --git a/third_party/WebKit/Source/core/editing/DOMSelection.cpp b/third_party/WebKit/Source/core/editing/DOMSelection.cpp
index d473161afba0f1e496fda0842d1b9f6079b6c2fb..5baad3bab0b5703e3fdb928a53a847f096b230f8 100644
--- a/third_party/WebKit/Source/core/editing/DOMSelection.cpp
+++ b/third_party/WebKit/Source/core/editing/DOMSelection.cpp
@@ -538,7 +538,12 @@ Range* DOMSelection::getRangeAt(unsigned index,
 }
 
 Range* DOMSelection::primaryRangeOrNull() const {
-  return rangeCount() > 0 ? getRangeAt(0, ASSERT_NO_EXCEPTION) : nullptr;
+  if (rangeCount() <= 0)
+    return nullptr;
+  Range* range = getRangeAt(0, ASSERT_NO_EXCEPTION);
+  if (!isSelectionOfDocument())

[yosin_UTC9, 2017/04/04 04:50:07]

I'm not a fan of this approach. We still create temporary Range.
Disposing it doesn't make execution speed, but we still have temporary object
eating GC heap up.

[yoichio, 2017/04/04 05:32:42]

Creating temporary Ranges and Disposing them is different matter.
At least disposing Range from document makes tree modification 
 faster though temporary Range is in heap.

I will implement somehow there is cached Range for each TreeScope 
 later.

[yosin_UTC9, 2017/04/04 07:21:31]

Calling Range::dispose() is error prone in this case and hacky.
Let's make clear code rather hacky code.

[tkent, 2017/04/04 08:41:24]

I agree that it's a hack :)
If we have no reason to be hurry, we should avoid this approach.

+    range->dispose();
+  return range;
 }
 
 EphemeralRange DOMSelection::createRangeFromSelectionEditor() const {