The attached patch: * Makes IndexToString and Int32ToString create Latin1 strings if Latin1 strings are enabled. Calling NewFatInlineString instead of NewGCFatInlineString also means we will create a non-fat inline string if possible, instead of always using a fat inline string. * Makes fun.toString() return a Latin1 string. This didn't work because ScriptSource::substring called NewStringCopyNDontDeflate, but only the asm.js caller wants this behavior so I added a separate substringDontDeflate for that. * Adds a jit-test to check that a large number of JS operations that return new strings create Latin1 strings. There are already tests for concatenation/substring etc so I didn't add those.