Fix large template file compilation problem

* SourceMap is not correctly generated and IOException (unexpected tag: 60) occurs 
  * when a compiled .scala has a string literal which size is longer than 32767 (== java.lang.Short.MAX_VALUE)
* The reason of this problem is the way to hande a Short value
  * since Short is **signed**, Short itself cannot handle unsigned 2 byte integer
* A Short value should be correctly converted to the Int value through `value & 0xFFFF` to resolve this problem
    * highest 16-bit in the Int value is cut.