Make StringCharCodeAt runtime function do what it name implies and not

test/mjsunit/string-charcodeat.js

Index: test/mjsunit/string-charcodeat.js
diff --git a/test/mjsunit/string-charcodeat.js b/test/mjsunit/string-charcodeat.js
index 392755775268600fd8fef6ed9d6ffc5c38ca2ffa..831f688fd4538c6cbd8b13b8c29bffc6a4759e4e 100644
--- a/test/mjsunit/string-charcodeat.js
+++ b/test/mjsunit/string-charcodeat.js
@@ -153,6 +153,10 @@ TestStringType(Slice16End, true);
 TestStringType(Flat16, true);
 TestStringType(NotAString16, true);
 
+for (var i = 0; i != 10; i++) {
+  assertEquals(101, Cons16().charCodeAt(1.1));
+  assertEquals('e', Cons16().charAt(1.1));
+}
 
 function StupidThing() {
   // Doesn't return a string from toString!