Merge pull request #1077 from mapbox/fix-style-change-crash

don't stop/start map in relation to style changes anymore since safe

platform/ios/MGLMapView.mm

@@ -192,17 +192,13 @@ mbgl::DefaultFileSource *mbglFileSource = nullptr;
     }
     else
     {
-        if ([@(mbglMap->getStyleJSON().c_str()) length]) mbglMap->stop();
         mbglMap->setStyleJSON((std::string)[styleJSON cStringUsingEncoding:[NSString defaultCStringEncoding]]);
-        mbglMap->start();
     }
 }
 
 - (void)setStyleURL:(NSString *)filePathURL
 {
-    if ([@(mbglMap->getStyleJSON().c_str()) length]) mbglMap->stop();
     mbglMap->setStyleURL(std::string("asset://") + [filePathURL UTF8String]);
-    mbglMap->start();
 }
 
 - (BOOL)commonInit
@@ -370,6 +366,9 @@ mbgl::DefaultFileSource *mbglFileSource = nullptr;
     _regionChangeDelegateQueue = [NSOperationQueue new];
     _regionChangeDelegateQueue.maxConcurrentOperationCount = 1;
 
+    // start the main loop
+    mbglMap->start();
+
     return YES;
 }