Removed Transform::needsTransition()

Transform::updateTransitions() already checks if there is a callback to
update transitions.

src/mbgl/map/map.cpp

@@ -73,11 +73,11 @@ bool Map::renderSync() {
 }
 
 void Map::nudgeTransitions(bool forceRerender) {
-    if (transform->needsTransition()) {
-        update(Update(transform->updateTransitions(Clock::now())));
-    } else if (forceRerender) {
-        update();
+    UpdateType update_ = transform->updateTransitions(Clock::now());
+    if (forceRerender) {
+        update_ |= static_cast<UpdateType>(Update::Repaint);
     }
+    update(Update(update_));
 }
 
 void Map::update(Update update_) {

src/mbgl/map/transform.cpp

@@ -377,10 +377,6 @@ void Transform::startTransition(std::function<Update(double)> frame,
     transitionFinishFn = finish;
 }
 
-bool Transform::needsTransition() const {
-    return !!transitionFrameFn;
-}
-
 UpdateType Transform::updateTransitions(const TimePoint& now) {
     return static_cast<UpdateType>(transitionFrameFn ? transitionFrameFn(now) : Update::Nothing);
 }

src/mbgl/map/transform.hpp

@@ -42,7 +42,6 @@ public:
     double getAngle() const;
 
     // Transitions
-    bool needsTransition() const;
     UpdateType updateTransitions(const TimePoint& now);
     void cancelTransitions();