Minor refactoring, be more tolerant w.r.t. vsync timings -> fixes Acid Drop.

src/emucore/tia/TIA.cxx

@@ -1116,7 +1116,7 @@ void TIA::onFrameStart()
   {
     // Only activate it when necessary, since changing colours in
     // the graphical object forces the TIA cached line to be flushed
-    if (myFrameManager->scanlineCountTransitioned())
+    if (myFrameManager->scanlineParityChanged())
     {
       myColorLossActive = myFrameManager->scanlinesLastFrame() & 0x1;
 

src/emucore/tia/frame-manager/AbstractFrameManager.hxx

@@ -92,10 +92,8 @@ class AbstractFrameManager : public Serializable
     /**
      * Did the number of scanlines switch between even / odd (used for color loss
      * emulation).
-     *
-     * TODO: Crappy name, find something better.
      */
-    bool scanlineCountTransitioned() const {
+    bool scanlineParityChanged() const {
       return (myPreviousFrameFinalLines & 0x1) != (myCurrentFrameFinalLines & 0x1);
     }
 

src/emucore/tia/frame-manager/FrameManager.cxx

@@ -29,7 +29,7 @@ enum Metrics: uInt32 {
   overscanNTSC                  = 30,
   overscanPAL                   = 36,
   vsync                         = 3,
-  maxLinesVsync                 = 32,
+  maxLinesVsync                 = 50,
   visibleOverscan               = 20,
   tvModeDetectionTolerance      = 20,
   initialGarbageFrames          = TIAConstants::initialGarbageFrames,