Rename Experimental transform to ESNext

1. Spread/rest are no longer experimental.
2. We need a place to put stage 3 ES features.

Jakefile.js

@@ -71,7 +71,7 @@ var compilerSources = [
     "transformers/destructuring.ts",
     "transformers/ts.ts",
     "transformers/jsx.ts",
-    "transformers/experimental.ts",
+    "transformers/esnext.ts",
     "transformers/es2017.ts",
     "transformers/es2016.ts",
     "transformers/es2015.ts",
@@ -108,7 +108,7 @@ var servicesSources = [
     "transformers/destructuring.ts",
     "transformers/ts.ts",
     "transformers/jsx.ts",
-    "transformers/experimental.ts",
+    "transformers/esnext.ts",
     "transformers/es2017.ts",
     "transformers/es2016.ts",
     "transformers/es2015.ts",

src/compiler/transformer.ts

@@ -1,7 +1,7 @@
 /// <reference path="visitor.ts" />
 /// <reference path="transformers/ts.ts" />
 /// <reference path="transformers/jsx.ts" />
-/// <reference path="transformers/experimental.ts" />
+/// <reference path="transformers/esnext.ts" />
 /// <reference path="transformers/es2017.ts" />
 /// <reference path="transformers/es2016.ts" />
 /// <reference path="transformers/es2015.ts" />
@@ -117,7 +117,7 @@ namespace ts {
             transformers.push(transformJsx);
         }
 
-        transformers.push(transformExperimental);
+        transformers.push(transformESNext);
         if (languageVersion < ScriptTarget.ES2017) {
             transformers.push(transformES2017);
         }

src/compiler/transformers/esnext.ts

@@ -3,7 +3,7 @@
 
 /*@internal*/
 namespace ts {
-    export function transformExperimental(context: TransformationContext) {
+    export function transformESNext(context: TransformationContext) {
         return transformSourceFile;
 
         function transformSourceFile(node: SourceFile) {

src/compiler/tsconfig.json

@@ -27,7 +27,7 @@
         "visitor.ts",
         "transformers/ts.ts",
         "transformers/jsx.ts",
-        "transformers/experimental.ts",
+        "transformers/esnext.ts",
         "transformers/es2017.ts",
         "transformers/es2016.ts",
         "transformers/es2015.ts",

src/harness/tsconfig.json

@@ -29,7 +29,7 @@
         "../compiler/visitor.ts",
         "../compiler/transformers/ts.ts",
         "../compiler/transformers/jsx.ts",
-        "../compiler/transformers/experimental.ts",
+        "../compiler/transformers/esnext.ts",
         "../compiler/transformers/es2017.ts",
         "../compiler/transformers/es2016.ts",
         "../compiler/transformers/es2015.ts",

src/services/tsconfig.json

@@ -28,7 +28,7 @@
         "../compiler/visitor.ts",
         "../compiler/transformers/ts.ts",
         "../compiler/transformers/jsx.ts",
-        "../compiler/transformers/experimental.ts",
+        "../compiler/transformers/esnext.ts",
         "../compiler/transformers/es2017.ts",
         "../compiler/transformers/es2016.ts",
         "../compiler/transformers/es2015.ts",