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/cli/cli-common/src/org/jetbrains/jet/cli/common/arguments/K2JSCompilerArguments.java

@@ -35,10 +35,6 @@ public class K2JSCompilerArguments extends CommonCompilerArguments {
     @ValueDescription("<path[,]>")
     public String[] libraryFiles;
 
-    @Argument(value = "sourceFiles", description = "Source files or directories separated by commas")
-    @ValueDescription("<path[,]>")
-    public String[] sourceFiles;
-
     @Argument(value = "sourcemap", description = "Generate SourceMap")
     public boolean sourcemap;