Blink does not respect input.selectionStart and input.selectionEnd for some cases

Source/core/html/HTMLTextFormControlElement.cpp

Index: Source/core/html/HTMLTextFormControlElement.cpp
diff --git a/Source/core/html/HTMLTextFormControlElement.cpp b/Source/core/html/HTMLTextFormControlElement.cpp
index bf3597a17159f2e0cad756e6e8be0ffc25b2bc4c..3d25bf7228369eb2cdd3c092c0c8a8d4a83d0238 100644
--- a/Source/core/html/HTMLTextFormControlElement.cpp
+++ b/Source/core/html/HTMLTextFormControlElement.cpp
@@ -164,12 +164,12 @@ void HTMLTextFormControlElement::updatePlaceholderVisibility(bool placeholderVal
 
 void HTMLTextFormControlElement::setSelectionStart(int start)
 {
-    setSelectionRange(start, max(start, selectionEnd()), selectionDirection());
+    setSelectionRange(start, max(start, selectionEndForJavascriptBindings()), selectionDirection());
 }
 
 void HTMLTextFormControlElement::setSelectionEnd(int end)
 {
-    setSelectionRange(min(end, selectionStart()), end, selectionDirection());
+    setSelectionRange(min(end, selectionStartForJavascriptBindings()), end, selectionDirection());
 }
 
 void HTMLTextFormControlElement::setSelectionDirection(const String& direction)
@@ -285,11 +285,21 @@ void HTMLTextFormControlElement::setSelectionRange(int start, int end, TextField
 
     end = max(end, 0);
     start = min(max(start, 0), end);
+    int textLength = innerTextValue().length();
+    if (textLength) {
+        if (textLength < start) {
+            start = textLength;
+            end = textLength;
+        } else if (textLength >= start && textLength < end) {

[Inactive, 2014/06/02 15:32:45]

nit: The "textLength >= start && " part seems unnecessary? (you are in the else
case of (textLength < start) so textLength has to be greater or equal to start
here).

[harpreet.sk, 2014/07/02 10:13:05]

Done.

+            end = textLength;
+        }
+    }
+    cacheSelection(start, end, direction);
+    bool isCaretSelection = (start == end);
+    bool shouldSetSelection = (document().focusedElement() == this) || (!isCaretSelection && start < textLength);

[tkent, 2014/06/01 23:40:55]

Why is !isCaretSelection necessary?

[harpreet.sk, 2014/07/02 10:13:05]

This check is necessary because when input is not focused we only shows
selection when it is not caret selection. The caret is not displayed if input is
not focused. Same behaviour  by firefox and IE.

 
-    if (!hasVisibleTextArea(renderer(), innerTextElement())) {
-        cacheSelection(start, end, direction);
+    if (!hasVisibleTextArea(renderer(), innerTextElement()))
         return;
-    }
     VisiblePosition startPosition = visiblePositionForIndex(start);
     VisiblePosition endPosition;
     if (start == end)
@@ -310,7 +320,8 @@ void HTMLTextFormControlElement::setSelectionRange(int start, int end, TextField
         newSelection = VisibleSelection(startPosition, endPosition);
     newSelection.setIsDirectional(direction != SelectionHasNoDirection);
 
-    if (LocalFrame* frame = document().frame())
+    LocalFrame* frame = document().frame();
+    if (frame && shouldSetSelection)
         frame->selection().setSelection(newSelection);
 }
 
@@ -341,12 +352,23 @@ int HTMLTextFormControlElement::selectionStart() const
 {
     if (!isTextFormControl())
         return 0;
-    if (document().focusedElement() != this)
+    if (document().focusedElement() != this) {
+        if (!innerTextValue().length())

[tkent, 2014/06/01 23:40:55]

As I wrote again and again, adjusting value on selectionStart/End getters would
be wrong.
Please fix the bug without updating selectionStart() and selectionEnd, and
without adding selection*ForJavaScriptBindings().

[harpreet.sk, 2014/07/02 10:13:05]

We require a check in selectionStart() and selectionEnd() for the case when
innerEditorValue() is empty because in only that case we would always return
value 0. Consider case below:

input.selectionStart = 3;
input.selectEnd = 5;

// Right now we have not set value. So when we check selectionStart/End it
shoudlreturn 0
// Now set value

input.value = "Parsed";

// Now selectionStart/End to be 3 and 5

I had removed the api selection*ForJavaScriptBindings() and try to adjust the
value in setSelectionStart/End.

+            return 0;
         return m_cachedSelectionStart;
+    }
 
     return computeSelectionStart();
 }
 
+int HTMLTextFormControlElement::selectionStartForJavascriptBindings() const
+{
+    if (!isTextFormControl())
+        return 0;
+
+    return m_cachedSelectionStart;
+}
+
 int HTMLTextFormControlElement::computeSelectionStart() const
 {
     ASSERT(isTextFormControl());
@@ -361,11 +383,22 @@ int HTMLTextFormControlElement::selectionEnd() const
 {
     if (!isTextFormControl())
         return 0;
-    if (document().focusedElement() != this)
+    if (document().focusedElement() != this) {
+        if (!innerTextValue().length())

[Inactive, 2014/06/02 15:32:45]

if (innerTextValue().isEmpty())

[harpreet.sk, 2014/07/02 10:13:05]

Done.

+            return 0;
         return m_cachedSelectionEnd;
+    }
     return computeSelectionEnd();
 }
 
+int HTMLTextFormControlElement::selectionEndForJavascriptBindings() const
+{
+    if (!isTextFormControl())
+        return 0;
+
+    return m_cachedSelectionEnd;
+}
+
 int HTMLTextFormControlElement::computeSelectionEnd() const
 {
     ASSERT(isTextFormControl());
@@ -478,8 +511,8 @@ void HTMLTextFormControlElement::selectionChanged(bool userTriggered)
     if (!renderer() || !isTextFormControl())
         return;
 
-    // selectionStart() or selectionEnd() will return cached selection when this node doesn't have focus
-    cacheSelection(computeSelectionStart(), computeSelectionEnd(), computeSelectionDirection());
+    if (document().focusedElement() == this)
+        cacheSelection(computeSelectionStart(), computeSelectionEnd(), computeSelectionDirection());
 
     if (LocalFrame* frame = document().frame()) {
         if (frame->selection().isRange() && userTriggered)