Unicode support in implementation of parseInt

[ruben-ayrapetyan]

Hello.

Implementation of parseInt (ecma-builtin-global.cpp) should be updated to use UTF-8 iterators for processing characters buffer.

Comment of @zherczeg in #394:

Is this correct? If I understand correctly, we just pass a byte, rather than an uint16_t character. I think we should rewrite this to use the UTF iterators, since there are line terminators and white spaces outside of the [0-127] byte range.

[galpeter]

Closing as this is fixed now.