RFR (S) 8136500: Integer/Long getChars and stringSize should be more idiomatic

[Ivan Gerasimov]

Thank you Aleksey!

>> Second, I think, the code of stringSize() might be better inlined, if it
>> was used only once.
> No-no! That's a helpful little fella. Not-yet-integrated Indify String
> Concat uses Integer/Long.stringSize.

I didn't really propose to manually inline the stringSize() into the 
calling code.
What I was trying to say was that if we replace the code "int size = (i 
< 0) ? stringSize(-i) + 1 : stringSize(i)", which calls stringSize() 
twice, with something, which calls it only once, it might be easier for 
compiler to inline it.

Sorry, I didn't make it clear :)

Sincerely yours,
Ivan