Re-factor/re-name the scripting getter, on the externalServices-implementations, to a createScripting method

Given that the GENERIC default viewer supports opening more than one document, and that a unique scripting-instance is now used for each document, the changes made in this patch seem appropriate.

web/app.js

@@ -168,6 +168,10 @@ class DefaultExternalServices {
     throw new Error("Not implemented: createL10n");
   }
 
+  static createScripting() {
+    throw new Error("Not implemented: createScripting");
+  }
+
   static get supportsIntegratedFind() {
     return shadow(this, "supportsIntegratedFind", false);
   }
@@ -186,10 +190,6 @@ class DefaultExternalServices {
   static get isInAutomation() {
     return shadow(this, "isInAutomation", false);
   }
-
-  static get scripting() {
-    throw new Error("Not implemented: scripting");
-  }
 }
 
 const PDFViewerApplication = {
@@ -1456,7 +1456,7 @@ const PDFViewerApplication = {
       // or the document was closed while the data resolved.
       return;
     }
-    const { scripting } = this.externalServices;
+    const scripting = this.externalServices.createScripting();
     // Store a reference to the current scripting-instance, to allow destruction
     // of the sandbox and removal of the event listeners at document closing.
     this._scriptingInstance = { scripting, events: new Map() };

web/chromecom.js

@@ -430,7 +430,7 @@ class ChromeExternalServices extends DefaultExternalServices {
     return new GenericL10n(navigator.language);
   }
 
-  static get scripting() {
+  static createScripting() {
     return new GenericScripting();
   }
 }

web/firefoxcom.js

@@ -360,7 +360,7 @@ class FirefoxExternalServices extends DefaultExternalServices {
     return new MozL10n(mozL10n);
   }
 
-  static get scripting() {
+  static createScripting() {
     return FirefoxScripting;
   }
 

web/genericcom.js

@@ -51,7 +51,7 @@ class GenericExternalServices extends DefaultExternalServices {
     return new GenericL10n(locale);
   }
 
-  static get scripting() {
+  static createScripting() {
     return new GenericScripting();
   }
 }