Remove deprecated API use

-rasterSampleCount was introduced as an alias for -sampleCount many
years ago, and now -sampleCount is deprecated. Switch to the modern
naming.

Fixed: dawn:2078
Change-Id: Ib027ea830b1b66d07c1d7f3e15563d77d019f7b1
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/152420
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>
Commit-Queue: Avi Drissman <avi@google.com>

src/dawn/native/metal/RenderPipelineMTL.mm

diff --git a/src/dawn/native/metal/RenderPipelineMTL.mm b/src/dawn/native/metal/RenderPipelineMTL.mm
index 0de8589..cc620a7 100644
--- a/src/dawn/native/metal/RenderPipelineMTL.mm
+++ b/src/dawn/native/metal/RenderPipelineMTL.mm
@@ -417,7 +417,7 @@
     }
 
     descriptorMTL.inputPrimitiveTopology = MTLInputPrimitiveTopology(GetPrimitiveTopology());
-    descriptorMTL.sampleCount = GetSampleCount();
+    descriptorMTL.rasterSampleCount = GetSampleCount();
     descriptorMTL.alphaToCoverageEnabled = IsAlphaToCoverageEnabled();
 
     NSError* error = nullptr;