Auto merge of #12932 - glennw:update-wr2, r=ConnorGBrewster

Update for webrender API change, and remove webrender specific hack

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- [ ] `./mach build -d` does not report any errors
- [ ] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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in display list building.

This relies on https://github.com/servo/webrender/pull/355 being
merged first, and will then need the cargo.lock updated.

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components/layout/display_list_builder.rs

@@ -1314,7 +1314,7 @@ impl FragmentDisplayListBuilding for Fragment {
                                -> Box<StackingContext> {
         let use_webrender = opts::get().use_webrender;
         let border_box = match mode {
-            StackingContextCreationMode::InnerScrollWrapper if !use_webrender => {
+            StackingContextCreationMode::InnerScrollWrapper => {
                 Rect::new(Point2D::zero(), base_flow.overflow.scroll.size)
             }
             _ => {

components/servo/Cargo.lock

@@ -2579,7 +2579,7 @@ dependencies = [
 [[package]]
 name = "webrender"
 version = "0.5.1"
-source = "git+https://github.com/servo/webrender#1c907208bcd4ad14f651383417a7031de92de6d4"
+source = "git+https://github.com/servo/webrender#2e9cba1c471b353babfb3bd80ec00207bc93f171"
 dependencies = [
  "app_units 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "bincode 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2604,7 +2604,7 @@ dependencies = [
 [[package]]
 name = "webrender_traits"
 version = "0.5.1"
-source = "git+https://github.com/servo/webrender#1c907208bcd4ad14f651383417a7031de92de6d4"
+source = "git+https://github.com/servo/webrender#2e9cba1c471b353babfb3bd80ec00207bc93f171"
 dependencies = [
  "app_units 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)",

ports/cef/Cargo.lock

@@ -2439,7 +2439,7 @@ dependencies = [
 [[package]]
 name = "webrender"
 version = "0.5.1"
-source = "git+https://github.com/servo/webrender#1c907208bcd4ad14f651383417a7031de92de6d4"
+source = "git+https://github.com/servo/webrender#2e9cba1c471b353babfb3bd80ec00207bc93f171"
 dependencies = [
  "app_units 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "bincode 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2464,7 +2464,7 @@ dependencies = [
 [[package]]
 name = "webrender_traits"
 version = "0.5.1"
-source = "git+https://github.com/servo/webrender#1c907208bcd4ad14f651383417a7031de92de6d4"
+source = "git+https://github.com/servo/webrender#2e9cba1c471b353babfb3bd80ec00207bc93f171"
 dependencies = [
  "app_units 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "byteorder 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)",