Drop "-sourceFiles" in kotlinc-js

Use free arguments instead, as is done in kotlinc-jvm and all sensible
compilers everywhere

Also fix some cases of AntTaskTest to be able to run them locally

compiler/testData/cli/js/jsHelp.out

@@ -2,7 +2,6 @@ Usage: kotlinc-js <options> <source files>
 where possible options include:
   -output <path>             Output file path
   -libraryFiles <path[,]>    Path to zipped library sources or kotlin files separated by commas
-  -sourceFiles <path[,]>     Source files or directories separated by commas
   -sourcemap                 Generate SourceMap
   -target <version>          Generate JS files for specific ECMA version (only ECMA 5 is supported)
   -main {call,noCall}        Whether a main function should be called; default 'call' (main function will be auto detected)