Fix setComposingText when newCursorPosition != 1

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

Index: third_party/WebKit/Source/core/editing/PlainTextRange.cpp
diff --git a/third_party/WebKit/Source/core/editing/PlainTextRange.cpp b/third_party/WebKit/Source/core/editing/PlainTextRange.cpp
index 7cfb84d3ba034f28437dd9c0c45e3f34382c3cb6..04b40313287814b6d6cc314fd635c2e949d43b83 100644
--- a/third_party/WebKit/Source/core/editing/PlainTextRange.cpp
+++ b/third_party/WebKit/Source/core/editing/PlainTextRange.cpp
@@ -148,8 +148,11 @@ EphemeralRange PlainTextRange::createRangeFor(const ContainerNode& scope, GetRan
         docTextPosition += len;
     }
 
-    if (!startRangeFound)
-        return EphemeralRange();
+    if (!startRangeFound) {

[Changwan Ryu, 2016/04/04 06:23:13]

Could you leave some comment on how startRangeFound is related to the right
boundary exceeding case?
Also, is there any genuine case where we want to return empty ephemeral range?
e.g. there was no text information in this node.

[yabinh, 2016/04/04 08:31:51]

OK.
startRangeFound = start() >= docTextPosition && start() <= docTextPosition +
len.
The former ensure new cursor doesn't exceed the left boundary, and the latter
ensures the right boundary.

In the old implementation, it will return empty ephemeral range if and only if
new cursor exceeds the boundary.

+        // If cursor position exceeds the right boundary, it should stay at the right boundary
+        resultStart = textRunEndPosition;
+        resultEnd = textRunEndPosition;
+    }
 
     if (length() && end() > docTextPosition) { // end() is out of bounds
         resultEnd = textRunEndPosition;