Refactor snapshot build (#2825)

Instead of using core/snapshot_creator.rs, instead two crates are
introduced which allow building the snapshot during build.rs.

Rollup is removed and replaced with our own bundler. This removes
the Node build dependency. Modules in //js now use Deno-style imports
with file extensions, rather than Node style extensionless imports.

This improves incremental build time when changes are made to //js files
by about 40 seconds.

1 files changed, 4 insertions, 4 deletions

diff --git a/js/write_file.ts b/js/write_file.ts
index c7b71725c..d6307e002 100644
--- a/js/write_file.ts
+++ b/js/write_file.ts
@@ -1,8 +1,8 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
-import { stat, statSync } from "./stat";
-import { open, openSync } from "./files";
-import { chmod, chmodSync } from "./chmod";
-import { writeAll, writeAllSync } from "./buffer";
+import { stat, statSync } from "./stat.ts";
+import { open, openSync } from "./files.ts";
+import { chmod, chmodSync } from "./chmod.ts";
+import { writeAll, writeAllSync } from "./buffer.ts";
 
 /** Options for writing to a file.
  * `perm` would change the file's permission if set.