wgpu::InputStepMode -> VertexStepMode

See https://github.com/gpuweb/gpuweb/pull/1927

Adds a typedef to make a gradual deprecation.

Bug: dawn:1023
Change-Id: Ic81a933a95556fbf5726056530788dde017a1449
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/59442
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Stephen White <senorblanco@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
diff --git a/examples/ComputeBoids.cpp b/examples/ComputeBoids.cpp
index 55ad9b7..72fff82 100644
--- a/examples/ComputeBoids.cpp
+++ b/examples/ComputeBoids.cpp
@@ -127,7 +127,7 @@
     descriptor.vertex.module = vsModule;
     descriptor.vertex.bufferCount = 2;
     descriptor.cBuffers[0].arrayStride = sizeof(Particle);
-    descriptor.cBuffers[0].stepMode = wgpu::InputStepMode::Instance;
+    descriptor.cBuffers[0].stepMode = wgpu::VertexStepMode::Instance;
     descriptor.cBuffers[0].attributeCount = 2;
     descriptor.cAttributes[0].offset = offsetof(Particle, pos);
     descriptor.cAttributes[0].format = wgpu::VertexFormat::Float32x2;