Review request: JDK-8157892: StackFrame::getFileName returns null when a source file exists for native methods

[Mandy Chung]

http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8157892/webrev.00/

This webrev addresses two issues [1][2].

It’s a simple fix to return proper filename that may be available for native 
method and fix getByteCodeIndex to check for a native method and returns proper 
value.

Mandy
[1] JDK-8157892: StackFrame::getFileName returns null when a source file exists 
for native methods
[2] JDK-8157977: getByteCodeIndex method from StackFrame does not return 
negative number when StackFrame is a native frame