[ios] Disable implicit animation of heading indicators

The update steps for the heading indicator are typically small, so animations tend to pile up and cause performance issues. Disabling actions is a slight regression when it comes to large steps (they're not animated now, where they previously were) and this should eventually be addressed.

Also consistently use provided API for disabling CATransaction actions.

platform/ios/src/MGLFaux3DUserLocationAnnotationView.m

@@ -71,7 +71,7 @@ - (void)updatePitch
     {
         // disable implicit animation
         [CATransaction begin];
-        [CATransaction setValue:(id)kCFBooleanTrue forKey:kCATransactionDisableActions];
+        [CATransaction setDisableActions:YES];
 
         CATransform3D t = CATransform3DRotate(CATransform3DIdentity, MGLRadiansFromDegrees(self.mapView.camera.pitch), 1.0, 0, 0);
         self.layer.sublayerTransform = t;
@@ -261,7 +261,12 @@ - (void)drawDot
             // Don't rotate if the change is imperceptible.
             if (fabs(rotation) > MGLUserLocationHeadingUpdateThreshold)
             {
+                [CATransaction begin];
+                [CATransaction setDisableActions:YES];
+
                 _headingIndicatorLayer.affineTransform = CGAffineTransformRotate(CGAffineTransformIdentity, rotation);
+
+                [CATransaction commit];
             }
         }
     }
@@ -283,10 +288,10 @@ - (void)drawDot
             _accuracyRingLayer.hidden = NO;
 
             // disable implicit animation of the accuracy ring, unless triggered by a change in accuracy
-            id shouldDisableActions = (_oldHorizontalAccuracy == self.userLocation.location.horizontalAccuracy) ? (id)kCFBooleanTrue : (id)kCFBooleanFalse;
+            BOOL shouldDisableActions = _oldHorizontalAccuracy == self.userLocation.location.horizontalAccuracy;
 
             [CATransaction begin];
-            [CATransaction setValue:shouldDisableActions forKey:kCATransactionDisableActions];
+            [CATransaction setDisableActions:shouldDisableActions];
 
             _accuracyRingLayer.bounds = CGRectMake(0, 0, accuracyRingSize, accuracyRingSize);
             _accuracyRingLayer.cornerRadius = accuracyRingSize / 2;