Re-factor how the "compatibility" values are specified in AppOptions

The intention with this change is to, more clearly, highlight when the default values may possibly be overridden by "compatibility" values.

web/app_options.js

@@ -96,7 +96,8 @@ const defaultOptions = {
    */
   maxCanvasPixels: {
     /** @type {number} */
-    value: viewerCompatibilityParams.maxCanvasPixels || 16777216,
+    value: 16777216,
+    compatibility: viewerCompatibilityParams.maxCanvasPixels,
     kind: OptionKind.VIEWER,
   },
   pdfBugEnabled: {
@@ -163,7 +164,8 @@ const defaultOptions = {
   },
   disableCreateObjectURL: {
     /** @type {boolean} */
-    value: apiCompatibilityParams.disableCreateObjectURL || false,
+    value: false,
+    compatibility: apiCompatibilityParams.disableCreateObjectURL,
     kind: OptionKind.API,
   },
   disableFontFace: {
@@ -241,22 +243,27 @@ class AppOptions {
   }
 
   static get(name) {
-    let defaultOption = defaultOptions[name], userOption = userOptions[name];
+    const userOption = userOptions[name];
     if (userOption !== undefined) {
       return userOption;
     }
-    return (defaultOption !== undefined ? defaultOption.value : undefined);
+    const defaultOption = defaultOptions[name];
+    if (defaultOption !== undefined) {
+      return (defaultOption.compatibility || defaultOption.value);
+    }
+    return undefined;
   }
 
   static getAll(kind = null) {
-    let options = Object.create(null);
-    for (let name in defaultOptions) {
-      let defaultOption = defaultOptions[name], userOption = userOptions[name];
-      if (kind && defaultOption.kind !== kind) {
+    const options = Object.create(null);
+    for (const name in defaultOptions) {
+      const defaultOption = defaultOptions[name];
+      if (kind && kind !== defaultOption.kind) {
         continue;
       }
-      options[name] = (userOption !== undefined ?
-                       userOption : defaultOption.value);
+      const userOption = userOptions[name];
+      options[name] = (userOption !== undefined ? userOption :
+                       (defaultOption.compatibility || defaultOption.value));
     }
     return options;
   }