Remove the cap on the number of iterations when tiling.

This could trigger spuriously for very long lines outside the view box. It
still indicates potential performance problem, but we shouldn't crash at least.

Closes #416.

Author: pcwalton

renderer/src/tiler.rs

@@ -224,12 +224,8 @@ fn process_line_segment(line_segment: LineSegment2F,
 
     let (mut current_position, mut tile_coords) = (line_segment.from(), from_tile_coords);
     let mut last_step_direction = None;
-    let mut iteration = 0;
 
     loop {
-        // Quick check to catch missing the end tile.
-        debug_assert!(iteration < MAX_ITERATIONS);
-
         let next_step_direction = if t_max.x() < t_max.y() {
             StepDirection::X
         } else if t_max.x() > t_max.y() {
@@ -302,11 +298,7 @@ fn process_line_segment(line_segment: LineSegment2F,
 
         current_position = next_position;
         last_step_direction = next_step_direction;
-
-        iteration += 1;
     }
-
-    const MAX_ITERATIONS: u32 = 1024;
 }
 
 #[derive(Clone, Copy, PartialEq, Debug)]