Backed out 2 changesets (bug 1535273) for webrender bustages CLOSED TREE

Backed out changeset ae26f98bfa7c (bug 1535273)
Backed out changeset df478b79c9b3 (bug 1535273)

[wrupdater] From https://hg.mozilla.org/mozilla-central/rev/9dcc555ea352f0dc8bdf58dc82bf57e4d0bfedd0

webrender/src/texture_allocator.rs

@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use api::units::{DeviceIntPoint, DeviceIntRect, DeviceIntSize};
+use util;
 
 //TODO: gather real-world statistics on the bin usage in order to assist the decision
 // on where to place the size thresholds.
@@ -166,10 +167,10 @@ impl ArrayAllocationTracker {
         }
 
         // Add the guillotined rects back to the free list.
-        if !new_free_rect_to_right.is_empty() {
+        if !util::rect_is_empty(&new_free_rect_to_right) {
             self.push(chosen.slice, new_free_rect_to_right);
         }
-        if !new_free_rect_to_bottom.is_empty() {
+        if !util::rect_is_empty(&new_free_rect_to_bottom) {
             self.push(chosen.slice, new_free_rect_to_bottom);
         }
     }

webrender/src/util.rs

@@ -4,9 +4,10 @@
 
 use api::BorderRadius;
 use api::units::*;
-use euclid::{TypedPoint2D, TypedRect, TypedSize2D, Vector2D};
+use euclid::{Point2D, Rect, Size2D, TypedPoint2D, TypedRect, TypedSize2D, Vector2D};
 use euclid::{TypedTransform2D, TypedTransform3D, TypedVector2D, TypedScale};
 use malloc_size_of::{MallocShallowSizeOf, MallocSizeOf, MallocSizeOfOps};
+use num_traits::Zero;
 use plane_split::{Clipper, Polygon};
 use std::{i32, f32, fmt, ptr};
 use std::borrow::Cow;
@@ -414,6 +415,12 @@ impl<U> RectHelpers<U> for TypedRect<f32, U> {
     }
 }
 
+// Don't use `euclid`'s `is_empty` because that has effectively has an "and" in the conditional
+// below instead of an "or".
+pub fn rect_is_empty<N: PartialEq + Zero, U>(rect: &TypedRect<N, U>) -> bool {
+    rect.size.width == Zero::zero() || rect.size.height == Zero::zero()
+}
+
 #[allow(dead_code)]
 #[inline]
 pub fn rect_from_points_f(x0: f32, y0: f32, x1: f32, y1: f32) -> Rect<f32> {