Add SelectionMode enum for setRangeText() in HTMLInputElement and HTMLTextAreaElement

LayoutTests/fast/forms/textarea/textarea-setrangetext-expected.txt

Index: LayoutTests/fast/forms/textarea/textarea-setrangetext-expected.txt
diff --git a/LayoutTests/fast/forms/textarea/textarea-setrangetext-expected.txt b/LayoutTests/fast/forms/textarea/textarea-setrangetext-expected.txt
index 9896cce27f059971a013ba89c8a9147c866a62fe..a729bc3d13875d18fb24b1179f6dbe64455d7300 100644
--- a/LayoutTests/fast/forms/textarea/textarea-setrangetext-expected.txt
+++ b/LayoutTests/fast/forms/textarea/textarea-setrangetext-expected.txt
@@ -77,10 +77,10 @@ PASS element.selectionStart is 6
 PASS element.selectionEnd is 9
 element.value = '0123456789'
 element.setSelectionRange(6, 9)
-element.setRangeText('AB', 1, 1, 'invalid')
-PASS element.value is "0AB123456789"
-PASS element.selectionStart is 8
-PASS element.selectionEnd is 11
+PASS element.setRangeText('AB', 1, 1, 'invalid') threw exception TypeError: Failed to execute 'setRangeText' on 'HTMLTextAreaElement': The provided value 'invalid' is not a valid enum value of type SelectionMode..
+PASS element.value is "0123456789"
+PASS element.selectionStart is 6
+PASS element.selectionEnd is 9
 element.value = '0123456789'
 element.setSelectionRange(6, 9)
 element.setRangeText('AB', 1, 1, undefined)
@@ -211,10 +211,10 @@ PASS element.selectionStart is 6
 PASS element.selectionEnd is 9
 element.value = '0123456789'
 element.setSelectionRange(6, 9)
-element.setRangeText('AB', 1, 1, 'invalid')
-PASS element.value is "0AB123456789"
-PASS element.selectionStart is 8
-PASS element.selectionEnd is 11
+PASS element.setRangeText('AB', 1, 1, 'invalid') threw exception TypeError: Failed to execute 'setRangeText' on 'HTMLTextAreaElement': The provided value 'invalid' is not a valid enum value of type SelectionMode..
+PASS element.value is "0123456789"
+PASS element.selectionStart is 6
+PASS element.selectionEnd is 9
 element.value = '0123456789'
 element.setSelectionRange(6, 9)
 element.setRangeText('AB', 1, 1, undefined)