web: Pass obfuscatedEventPrefix via query string

This eliminates the need to create a script dynamically, and fixes
publicPath() to correctly return the extension URL rather than the
host site URL.

web/packages/extension/js/index.js

@@ -7,6 +7,25 @@ window.RufflePlayer = PublicAPI.negotiate(
 );
 __webpack_public_path__ = publicPath(window.RufflePlayer.config, "extension");
 
+function getObfuscatedEventPrefix() {
+    if (
+        document.currentScript !== undefined &&
+        document.currentScript !== null &&
+        "src" in document.currentScript &&
+        document.currentScript.src !== ""
+    ) {
+        // Default to the directory where this script resides.
+        try {
+            return new URL(document.currentScript.src).searchParams.get(
+                "obfuscatedEventPrefix"
+            );
+        } catch (e) {
+            return null;
+        }
+    }
+}
+
+const obfuscatedEventPrefix = getObfuscatedEventPrefix();
 if (obfuscatedEventPrefix) {
     document.addEventListener(obfuscatedEventPrefix + "_request", function (e) {
         let body = JSON.parse(e.detail);

web/packages/extension/js/lv0.js

@@ -139,8 +139,6 @@ getSyncStorage(["ruffleEnable", "ignoreOptout"], function (data) {
         }
     });
 
-    const extPath = getExtensionUrl();
-
     if (shouldLoadUntrustedWorld) {
         // We must run the plugin polyfill before any flash detection scripts.
         // Unfortunately, this might still be too late for some websites when using Chrome (issue #969).
@@ -151,22 +149,13 @@ getSyncStorage(["ruffleEnable", "ignoreOptout"], function (data) {
 
         // Load Ruffle script asynchronously. By doing so, we can inject extra variables and isolate them from the global scope.
         (async function () {
-            let ruffleSrcResp = await fetch(extPath + "dist/ruffle.js");
-            if (ruffleSrcResp.ok) {
-                let ruffleSource =
-                    '(function () { var obfuscatedEventPrefix = "' +
-                    obfuscatedEventPrefix +
-                    '";\n' +
-                    (await ruffleSrcResp.text()) +
-                    "}())";
-                let ruffleScript = document.createElement("script");
-                ruffleScript.appendChild(document.createTextNode(ruffleSource));
-                (document.head || document.documentElement).appendChild(
-                    ruffleScript
-                );
-            } else {
-                console.error("Critical error loading Ruffle into page");
-            }
+            const ruffleScript = document.createElement("script");
+            ruffleScript.src = getExtensionUrl(
+                `dist/ruffle.js?obfuscatedEventPrefix=${obfuscatedEventPrefix}`
+            );
+            (document.head || document.documentElement).appendChild(
+                ruffleScript
+            );
         })();
     }
 });

web/packages/extension/js/util.js

@@ -213,15 +213,11 @@ function setMessageListener(listener) {
     }
 }
 
-function getExtensionUrl() {
+function getExtensionUrl(path) {
     if (chrome && chrome.extension && chrome.extension.getURL) {
-        return chrome.extension
-            .getURL("dist/ruffle.js")
-            .replace("dist/ruffle.js", "");
+        return chrome.extension.getURL(path);
     } else if (browser && browser.runtime && browser.runtime.getURL) {
-        return browser.runtime
-            .getURL("dist/ruffle.js")
-            .replace("dist/ruffle.js", "");
+        return browser.runtime.getURL(path);
     } else {
         console.error("Couldn't get extension URL");
     }