Merge pull request #4077 from Leaflet/fix-2427

When limiting center to bounds, ignore offsets less than a pixel.

src/map/Map.js

@@ -790,6 +790,13 @@ L.Map = L.Evented.extend({
 		    viewBounds = new L.Bounds(centerPoint.subtract(viewHalf), centerPoint.add(viewHalf)),
 		    offset = this._getBoundsOffset(viewBounds, bounds, zoom);
 
+		// If offset is less than a pixel, ignore.
+		// This prevents unstable projections from getting into
+		// an infinite loop of tiny offsets.
+		if (offset.round().equals([0, 0])) {
+			return center;
+		}
+
 		return this.unproject(centerPoint.add(offset), zoom);
 	},