Bug 686514 - Make ctrl-plus and ctrl-minus scale image documents. r=gavin.sharp,jonas

content/base/public/nsIDocument.h

@@ -1600,6 +1600,8 @@ public:
   void WarnOnceAbout(DeprecatedOperations aOperation);
 
   virtual void PostVisibilityUpdateEvent() = 0;
+  
+  bool IsSyntheticDocument() { return mIsSyntheticDocument; }
 
   void SetNeedLayoutFlush() {
     mNeedLayoutFlush = true;

content/events/src/nsEventStateManager.cpp

@@ -2516,7 +2516,7 @@ nsEventStateManager::DoScrollZoom(nsIFrame *aTargetFrame,
       // positive adjustment to decrease zoom, negative to increase
       PRInt32 change = (adjustment > 0) ? -1 : 1;
 
-      if (Preferences::GetBool("browser.zoom.full")) {
+      if (Preferences::GetBool("browser.zoom.full") || content->GetCurrentDoc()->IsSyntheticDocument()) {
         ChangeFullZoom(change);
       } else {
         ChangeTextSize(change);

toolkit/content/viewZoomOverlay.js

@@ -79,8 +79,9 @@ var ZoomManager = {
   getZoomForBrowser: function ZoomManager_getZoomForBrowser(aBrowser) {
     var markupDocumentViewer = aBrowser.markupDocumentViewer;
 
-    return this.useFullZoom ? markupDocumentViewer.fullZoom
-                            : markupDocumentViewer.textZoom;
+    return this.useFullZoom || 
+      aBrowser.contentDocument.mozSyntheticDocument ?
+      markupDocumentViewer.fullZoom : markupDocumentViewer.textZoom;
   },
 
   set zoom(aVal) {
@@ -94,7 +95,7 @@ var ZoomManager = {
 
     var markupDocumentViewer = aBrowser.markupDocumentViewer;
 
-    if (this.useFullZoom) {
+    if (this.useFullZoom || aBrowser.contentDocument.mozSyntheticDocument) {
       markupDocumentViewer.textZoom = 1;
       markupDocumentViewer.fullZoom = aVal;
     } else {