make shadowed function findParent target finder more reliable

src/babel/transformation/transformers/es6/parameters/default.js

@@ -38,7 +38,7 @@ export var visitor = {
 
     //
     var argsIdentifier = t.identifier("arguments");
-    argsIdentifier._shadowedFunctionLiteral = node;
+    argsIdentifier._shadowedFunctionLiteral = this;
 
     // push a default parameter definition
     function pushDefNode(left, right, i) {

src/babel/transformation/transformers/es6/parameters/rest.js

@@ -84,7 +84,7 @@ export var visitor = {
     var argsId = t.identifier("arguments");
 
     // otherwise `arguments` will be remapped in arrow functions
-    argsId._shadowedFunctionLiteral = node;
+    argsId._shadowedFunctionLiteral = this;
 
     // support patterns
     if (t.isPattern(rest)) {

src/babel/transformation/transformers/es6/tail-call.js

@@ -211,7 +211,7 @@ class TailCallTransformer {
       var decl = t.variableDeclarator(this.argumentsId);
       if (this.argumentsId) {
         decl.init = t.identifier("arguments");
-        decl.init._shadowedFunctionLiteral = node;
+        decl.init._shadowedFunctionLiteral = this.path;
       }
       topVars.push(decl);
     }

src/babel/transformation/transformers/internal/shadow-functions.js

@@ -9,15 +9,31 @@ function remap(path, key, create) {
   if (!path.inShadow()) return;
 
   var shadowed = path.node._shadowedFunctionLiteral;
+  var currentFunction;
 
   var fnPath = path.findParent(function (path) {
     if (shadowed) {
-      return path.node === shadowed;
+      // only match our shadowed function parent
+      if (path === shadowed) {
+        // found our target reference function
+        currentFunction = path;
+        return true;
+      } else {
+        return false;
+      }
+    } else if (path.isFunction() || path.isProgram()) {
+      // catch current function in case this is the shadowed one
+      if (!currentFunction) currentFunction = path;
+
+      return !path.is("shadow");
     } else {
-      return !path.is("shadow") && (path.isFunction() || path.isProgram());
+      return false;
     }
   });
 
+  // no point in realiasing if we're in this function
+  if (fnPath === currentFunction) return;
+
   var cached = fnPath.getData(key);
   if (cached) return cached;