Remove unneeded parsing of optional-size when parsing array types

When the VM parses an array type in a method signature, it looks for one or more of the following at the start of the array type: "[<optional-size>", where <optional-size> is zero or more digits. (See SignatureIterator::parse_type() in signature.cpp, and other places)

The <optional-size> is not in the JVM-Spec and does not appear to be used. The code that parses it should be removed if an <optional-size> of one or more digits is never specified.