wasm-bindgen-rayon and new OMT plugin (#1007)

* WIP: wasm-bindgen-rayon and new OMT plugin

* Bump package-lock

* Make OMT work again

* Update year

* Restore accidental change

* Prevent minification of `nextDefineUri`

* Delay loading external deps

This gives inline `define` calls a chance to define dependencies for earlier `define` calls on the same page.

* Add comment

lib/omt.ejs

@@ -1,5 +1,5 @@
 /**
- * Copyright 2020 Google Inc. All Rights Reserved.
+ * Copyright 2021 Google Inc. All Rights Reserved.
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
@@ -13,80 +13,64 @@
 
 // If the loader is already loaded, just stop.
 if (!self.<%- amdFunctionName %>) {
-  const singleRequire = async name => {
-    if (name === 'require') return require;
-    let url;
-    if (name.startsWith(location.origin)) {
-      url = name.slice(location.origin.length);
-    } else {
-      url = name.slice(1) + '.js';
-    }
-    if (!url.startsWith('/c/')) {
-      url = '/c' + url;
-    }
-    name = './static' + url;
-    if (registry[name]) return registry[name];
+  let registry = {};
 
-    if (!registry[name]) {
+  const singleRequire = (uri, parentUri) => {
+    let origURI = uri;
+    uri = new URL(uri + ".js", parentUri).href;
+    return registry[uri] || (
       <% if (useEval) { %>
-        const text = await fetch(url).then(resp => resp.text());
-        eval(text);
+        fetch(uri)
+          .then(resp => resp.text())
+          .then(code => {
+            self.nextDefineUri = uri;
+            eval(code);
+          })
       <% } else { %>
-        if ("document" in self) {
-          await new Promise(resolve => {
+        new Promise(resolve => {
+          if ("document" in self) {
             const script = document.createElement("script");
-            script.src = url;
-            document.head.appendChild(script);
+            script.src = uri;
             script.onload = resolve;
-          });
-        } else {
-          importScripts(url);
-        }
+            document.head.appendChild(script);
+          } else {
+            self.nextDefineUri = uri;
+            importScripts(uri);
+            resolve();
+          }
+        })
       <% } %>
-    }
-    if (!registry[name]) {
-      throw new Error(`Module ${name} didn’t register its module`);
-    }
-    return registry[name];
+      .then(() => {
+        let promise = registry[uri];
+        if (!promise) {
+          throw new Error(`Module ${uri} didn’t register its module`);
+        }
+        return promise;
+      })
+    );
   };
 
-  const require = (names, resolve) => {
-    Promise.all(names.map(singleRequire))
-      .then(modules => resolve(modules.length === 1 ? modules[0] : modules));
-  };
-
-  const registry = {
-    require: Promise.resolve(require)
-  };
-
-  self.<%- amdFunctionName %> = (moduleName, depsNames, factory) => {
-    if (registry[moduleName]) {
+  self.<%- amdFunctionName %> = (depsNames, factory) => {
+    const uri = self.nextDefineUri || ("document" in self ? document.currentScript.src : "") || location.href;
+    if (registry[uri]) {
       // Module is already loading or loaded.
       return;
     }
-    registry[moduleName] = Promise.resolve().then(() => {
-      let exports = {};
-      const module = {
-        uri: location.origin + moduleName.slice(1)
-      };
-      return Promise.all(
-        depsNames.map(depName => {
-          switch(depName) {
-            case "exports":
-              return exports;
-            case "module":
-              return module;
-            default:
-              return singleRequire(depName);
-          }
-        })
-      ).then(deps => {
-        const facValue = factory(...deps);
-        if (!exports.default) {
-          exports.default = facValue;
-        }
-        return exports;
-      });
+    let exports = {};
+    const require = depUri => singleRequire(depUri, uri);
+    const specialDeps = {
+      module: { uri },
+      exports,
+      require
+    };
+    // Note: Promise.resolve() is necessary to delay loading until all the
+    // `define`s on the current page had a chance to execute first.
+    // This allows to inline some deps on the main page.
+    registry[uri] = Promise.resolve().then(() => Promise.all(depsNames.map(
+      depName => specialDeps[depName] || require(depName)
+    ))).then(deps => {
+      factory(...deps);
+      return exports;
     });
   };
 }