Use Position instead of VisiblePosition for SurroundingText.

Source/core/editing/SurroundingText.cpp

Index: Source/core/editing/SurroundingText.cpp
diff --git a/Source/core/editing/SurroundingText.cpp b/Source/core/editing/SurroundingText.cpp
index cefe4005a39eb0a239b7d95b177dff9a0aeb1182..1d23c6ab5afeaa08a82ad89ca7054f71bee38ff9 100644
--- a/Source/core/editing/SurroundingText.cpp
+++ b/Source/core/editing/SurroundingText.cpp
@@ -32,38 +32,48 @@
 #include "core/editing/SurroundingText.h"
 
 #include "core/dom/Document.h"
+#include "core/dom/Position.h"
 #include "core/dom/Range.h"
 #include "core/editing/TextIterator.h"
-#include "core/editing/VisiblePosition.h"
-#include "core/editing/VisibleUnits.h"
 
 namespace WebCore {
 
-SurroundingText::SurroundingText(const VisiblePosition& visiblePosition, unsigned maxLength)
+SurroundingText::SurroundingText(const Position& position, unsigned maxLength)
     : m_positionOffsetInContent(0)
 {
-    if (visiblePosition.isNull())
+    if (position.isNull())
         return;
 
     const unsigned halfMaxLength = maxLength / 2;
-    CharacterIterator forwardIterator(makeRange(visiblePosition, endOfDocument(visiblePosition)).get(), TextIteratorStopsOnFormControls);
-    if (!forwardIterator.atEnd())
-        forwardIterator.advance(maxLength - halfMaxLength);
 
-    Position position = visiblePosition.deepEquivalent().parentAnchoredEquivalent();
     Document* document = position.document();
     ASSERT(document);

[yosin_UTC9, 2014/06/04 01:04:05]

nit: We don't need to have this |ASSERT(document)|, because we check
|Position.isNull()| on L44.

[yosin_UTC9, 2014/06/04 01:13:10]

How about unify |Position::isNull| and |Position::document|?

Document* document = position.document();
if (!document)
   return;

[mlamouri (slow - plz ping), 2014/06/04 09:52:12]

Done.

-    RefPtrWillBeRawPtr<Range> forwardRange = forwardIterator.range();
+
+    // The forward range starts at the selection end and ends at the document's
+    // end. It will then be updated to only contain the text in the text in the
+    // right range around the selection.
+    RefPtrWillBeRawPtr<Range> forwardRange = rangeOfContents(document);
+    forwardRange->setStart(position);
+    CharacterIterator forwardIterator(forwardRange.get(), TextIteratorStopsOnFormControls);
+    if (!forwardIterator.atEnd())
+        forwardIterator.advance(maxLength - halfMaxLength);
+
+    forwardRange = forwardIterator.range();
     if (!forwardRange || !Range::create(*document, position, forwardRange->startPosition())->text().length()) {
         ASSERT(forwardRange);
         return;
     }
 
-    BackwardsCharacterIterator backwardsIterator(makeRange(startOfDocument(visiblePosition), visiblePosition).get(), TextIteratorStopsOnFormControls);
+    // Same as with the forward range but with the backward range. The range
+    // starts at the document's start and ends at the selection start and will
+    // be updated.
+    RefPtrWillBeRawPtr<Range> backwardsRange = rangeOfContents(document);
+    backwardsRange->setEnd(position);
+    BackwardsCharacterIterator backwardsIterator(backwardsRange.get(), TextIteratorStopsOnFormControls);
     if (!backwardsIterator.atEnd())
         backwardsIterator.advance(halfMaxLength);
 
-    RefPtrWillBeRawPtr<Range> backwardsRange = backwardsIterator.range();
+    backwardsRange = backwardsIterator.range();
     if (!backwardsRange) {
         ASSERT(backwardsRange);
         return;