Text API does not behave according to specification

LayoutTests/fast/dom/text-api-arguments-expected.txt

+Tests that the Text API arguments are correctly validated.
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS text.data is "abcdefg"
+PASS text.__proto__ is Text.prototype
+PASS text.splitText(4).data is "efg"
+PASS text.data is "abcd"
+PASS text.splitText() threw exception TypeError: Not enough arguments.
+PASS text.data is "abcd"
+PASS text.splitText(999) threw exception IndexSizeError: Index or size was negative, or greater than the allowed value..
+PASS text.data is "abcd"
+PASS text.splitText(-1) threw exception IndexSizeError: Index or size was negative, or greater than the allowed value..
+PASS text.data is "abcd"
+PASS text.splitText(-4294967294).data is "cd"
+PASS text.data is "ab"
+PASS text.replaceWholeText('test') is text
+PASS text.data is "test"
+PASS text.replaceWholeText('') is null
+PASS text.data is "test"
+PASS text.replaceWholeText() threw exception TypeError: Not enough arguments.
+PASS text.data is "test"
+PASS text.replaceWholeText(null) is text
+PASS text.data is "null"
+PASS text.replaceWholeText(undefined) is text
+PASS text.data is "undefined"
+PASS successfullyParsed is true
+
+TEST COMPLETE
+