Selection API: Selection.extend() should throw if rangeCount is 0.

third_party/WebKit/LayoutTests/editing/execCommand/transpose-backslash-with-euc.html

Index: third_party/WebKit/LayoutTests/editing/execCommand/transpose-backslash-with-euc.html
diff --git a/third_party/WebKit/LayoutTests/editing/execCommand/transpose-backslash-with-euc.html b/third_party/WebKit/LayoutTests/editing/execCommand/transpose-backslash-with-euc.html
index a38b1e915f2848392a1e5348f3bc53a93f857adb..22bea6511ec447625ad3b8ab3f70401bb02ac301 100644
--- a/third_party/WebKit/LayoutTests/editing/execCommand/transpose-backslash-with-euc.html
+++ b/third_party/WebKit/LayoutTests/editing/execCommand/transpose-backslash-with-euc.html
@@ -11,6 +11,7 @@ if (window.testRunner)
 function test()
 {
     var backslashDivElement = document.getElementById("backslash");
+    backslashDivElement.focus();

[yosin_UTC9, 2017/02/09 01:33:18]

I think it is better to write: |getSelection().collapse(backslashDivElement, 0)|
rather than
setting focus to |backslashDivElement| to set selection to backslashDivElement@0
and we
don't need to set focus to content editable for execCommand.

This tells me that we should not set focus by Selection#collapse() and
Selection#extend().

[tkent, 2017/02/09 02:06:17]

Done.

[yosin_UTC9, 2017/02/09 02:26:30]

I filed [1].

http://crbug.com/690272 Selection#collapse,collapseTo{Start,End},extend() should
not move focus

     getSelection().extend(backslashDivElement, 1);
     document.execCommand("Transpose");