Source map support (#429)

This change increases size:
out/debug/obj/libdeno/from_snapshot.o  19M -> 34M
out/release/deno                       32M -> 47M

1 files changed, 23 insertions, 10 deletions

diff --git a/js/runtime.ts b/js/runtime.ts
index 79f463759..4e9cb657d 100644
--- a/js/runtime.ts
+++ b/js/runtime.ts
@@ -12,7 +12,7 @@ import * as util from "./util";
 import { log } from "./util";
 import { assetSourceCode } from "./assets";
 import * as os from "./os";
-//import * as sourceMaps from "./v8_source_maps";
+import * as sourceMaps from "./v8_source_maps";
 import { window, globalEval } from "./globals";
 //import * as deno from "./deno";
 
@@ -39,26 +39,39 @@ window.onerror = (
   os.exit(1);
 };
 
-/*
-export function setup(mainJs: string, mainMap: string): void {
+// This is called during snapshot creation with the contents of
+// out/debug/gen/bundle/main.js.map.
+import { RawSourceMap } from "source-map";
+let mainSourceMap: RawSourceMap = null;
+function setMainSourceMap(rawSourceMap: RawSourceMap) {
+  util.assert(Number(rawSourceMap.version) === 3);
+  mainSourceMap = rawSourceMap;
+}
+window["setMainSourceMap"] = setMainSourceMap;
+
+export function setup(): void {
   sourceMaps.install({
     installPrepareStackTrace: true,
-    getGeneratedContents: (filename: string): string => {
-      if (filename === "/main.js") {
-        return mainJs;
-      } else if (filename === "/main.map") {
-        return mainMap;
+    getGeneratedContents: (filename: string): string | RawSourceMap => {
+      util.log("getGeneratedContents", filename);
+      if (filename === "gen/bundle/main.js") {
+        util.assert(window["mainSource"].length > 0);
+        return window["mainSource"];
+      } else if (filename === "main.js.map") {
+        return mainSourceMap;
+      } else if (filename === "deno_main.js") {
+        return "";
       } else {
         const mod = FileModule.load(filename);
         if (!mod) {
-          console.error("getGeneratedContents cannot find", filename);
+          util.log("getGeneratedContents cannot find", filename);
+          return null;
         }
         return mod.outputCode;
       }
     }
   });
 }
-*/
 
 // This class represents a module. We call it FileModule to make it explicit
 // that each module represents a single file.