[mv3] Honor scriptlets' target world in Firefox

When the target world of a scriptlet is the ISOLATED one,
skip Blob-based injection in Firefox, as the current world
is always the ISOLATED one. This should make ISOLATED
world-based scriptlets more reliable (i.e. execute sooner)
in Firefox.

platform/mv3/make-scriptlets.js

@@ -59,6 +59,7 @@ export function init() {
         const entry = {
             name: fn.name,
             code: fn.toString(),
+            world: scriptlet.world || 'MAIN',
             dependencies: scriptlet.dependencies,
             requiresTrust: scriptlet.requiresTrust === true,
         };
@@ -96,6 +97,7 @@ export function compile(details) {
         scriptletFiles.set(scriptletToken, {
             name: resourceEntry.name,
             code: createScriptletCoreCode(scriptletToken),
+            world: resourceEntry.world,
             args: new Map(),
             hostnames: new Map(),
             entities: new Map(),
@@ -165,6 +167,7 @@ export async function commit(rulesetId, path, writeFn) {
         );
         content = safeReplace(content, /\$rulesetId\$/, rulesetId, 0);
         content = safeReplace(content, /\$scriptletName\$/, details.name, 0);
+        content = safeReplace(content, '$world$', details.world);
         content = safeReplace(content,
             'self.$argsList$',
             JSON.stringify(Array.from(details.args.keys()).map(a => JSON.parse(a)))

platform/mv3/scriptlets/scriptlet.template.js

@@ -132,8 +132,10 @@ argsList.length = 0;
 //   'MAIN' world not yet supported in Firefox, so we inject the code into
 //   'MAIN' ourself when environment in Firefox.
 
+const targetWorld = '$world$';
+
 // Not Firefox
-if ( typeof wrappedJSObject !== 'object' ) {
+if ( typeof wrappedJSObject !== 'object' || targetWorld === 'ISOLATED' ) {
     return uBOL_$scriptletName$();
 }