Correct source map paths for babel-register. (#3523)

packages/babel-register/src/node.js

@@ -48,8 +48,11 @@ function compile(filename) {
   let result;
 
   // merge in base options and resolve all the plugins and presets relative to this file
+  let relativePath = getRelativePath(filename);
   let opts = new OptionManager().init(extend(deepClone(transformOpts), {
-    filename
+    filename,
+    sourceMapTarget: relativePath,
+    sourceFileName: relativePath,
   }));
 
   let cacheKey = `${JSON.stringify(opts)}:${babel.version}`;