add loose mode to spread and destructuring

lib/6to5/transformation/transformers/es6-destructuring.js

@@ -7,7 +7,7 @@ var buildVariableAssign = function (opts, id, init) {
   if (t.isMemberExpression(id)) op = "=";
 
   if (op) {
-    return t.expressionStatement(t.assignmentExpression("=", id, init));
+    return t.expressionStatement(t.assignmentExpression(op, id, init));
   } else {
     return t.variableDeclaration(opts.kind, [
       t.variableDeclarator(id, init)
@@ -95,7 +95,12 @@ var pushArrayPattern = function (opts, nodes, pattern, parentId) {
     }
   }
 
-  var toArray = opts.file.toArray(parentId, !hasSpreadElement && pattern.elements.length);
+  var isLoose = opts.file.isLoose("destructuring");
+  var toArray = parentId;
+
+  if (!isLoose) {
+    toArray = opts.file.toArray(parentId, !hasSpreadElement && pattern.elements.length);
+  }
 
   var _parentId = opts.scope.generateUidBasedOnNode(parentId, opts.file);
   nodes.push(t.variableDeclaration("var", [
@@ -107,12 +112,14 @@ var pushArrayPattern = function (opts, nodes, pattern, parentId) {
     var elem = pattern.elements[i];
     if (!elem) continue;
 
-    i = +i;
-
     var newPatternId;
 
     if (t.isSpreadElement(elem)) {
-      newPatternId = opts.file.toArray(parentId);
+      newPatternId = parentId;
+
+      if (!isLoose) {
+        newPatternId = opts.file.toArray(parentId);
+      }
 
       if (i > 0) {
         newPatternId = t.callExpression(t.memberExpression(newPatternId, t.identifier("slice")), [t.literal(i)]);

lib/6to5/transformation/transformers/es6-spread.js

@@ -2,7 +2,11 @@ var t = require("../../types");
 var _ = require("lodash");
 
 var getSpreadLiteral = function (spread, file) {
-  return file.toArray(spread.argument);
+  if (file.isLoose("spread")) {
+    return spread.argument;
+  } else {
+    return file.toArray(spread.argument);
+  }
 };
 
 var hasSpread = function (nodes) {
@@ -64,7 +68,7 @@ exports.CallExpression = function (node, parent, scope, context, file) {
   node.arguments = [];
 
   var nodes;
-  if (args.length === 1 && args[0].argument.name === 'arguments') {
+  if (args.length === 1 && args[0].argument.name === "arguments") {
     nodes = [args[0].argument];
   } else {
     nodes = build(args, file);