reorg: cli/js/compiler/, move more API to cli/js/web/ (#4310)

- moves compiler implementation to "cli/js/compiler/" directory
- moves more APIs to "cli/js/web":
    * "console.ts"
    * "console_table.ts"
    * "performance.ts"
    * "timers.ts"
    * "workers.ts"
- removes some dead code from "cli/js/"

cli/js/compiler/bootstrap.ts

@@ -0,0 +1,52 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import { CompilerHostTarget, Host } from "./host.ts";
+import { ASSETS } from "./sourcefile.ts";
+import { getAsset } from "./util.ts";
+
+// NOTE: target doesn't really matter here,
+// this is in fact a mock host created just to
+// load all type definitions and snapshot them.
+const host = new Host({
+  target: CompilerHostTarget.Main,
+  writeFile(): void {}
+});
+const options = host.getCompilationSettings();
+
+// This is a hacky way of adding our libs to the libs available in TypeScript()
+// as these are internal APIs of TypeScript which maintain valid libs
+ts.libs.push("deno.ns", "deno.window", "deno.worker", "deno.shared_globals");
+ts.libMap.set("deno.ns", "lib.deno.ns.d.ts");
+ts.libMap.set("deno.window", "lib.deno.window.d.ts");
+ts.libMap.set("deno.worker", "lib.deno.worker.d.ts");
+ts.libMap.set("deno.shared_globals", "lib.deno.shared_globals.d.ts");
+
+// this pre-populates the cache at snapshot time of our library files, so they
+// are available in the future when needed.
+host.getSourceFile(`${ASSETS}/lib.deno.ns.d.ts`, ts.ScriptTarget.ESNext);
+host.getSourceFile(`${ASSETS}/lib.deno.window.d.ts`, ts.ScriptTarget.ESNext);
+host.getSourceFile(`${ASSETS}/lib.deno.worker.d.ts`, ts.ScriptTarget.ESNext);
+host.getSourceFile(
+  `${ASSETS}/lib.deno.shared_globals.d.ts`,
+  ts.ScriptTarget.ESNext
+);
+
+/**
+ * This function spins up TS compiler and loads all available libraries
+ * into memory (including ones specified above).
+ *
+ * Used to generate the foundational AST for all other compilations, so it can
+ * be cached as part of the snapshot and available to speed up startup.
+ */
+export const TS_SNAPSHOT_PROGRAM = ts.createProgram({
+  rootNames: [`${ASSETS}/bootstrap.ts`],
+  options,
+  host
+});
+
+/** A module loader which is concatenated into bundle files.
+ *
+ * We read all static assets during the snapshotting process, which is
+ * why this is located in compiler_bootstrap.
+ */
+export const SYSTEM_LOADER = getAsset("system_loader.js");