dawn_node: Fix conversion of BlendState

A silly typo was causing a large number of blending tests to fail.

Bug: dawn:1123
Change-Id: Ib6423ad6c58baab2db15034633f95bab7b0c7912
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/65401
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>

src/dawn_node/binding/Converter.cpp

@@ -507,7 +507,7 @@ namespace wgpu { namespace binding {
 
     bool Converter::Convert(wgpu::BlendState& out, const interop::GPUBlendState& in) {
         out = {};
-        return Convert(out.alpha, in.alpha) && Convert(out.color, in.alpha);
+        return Convert(out.alpha, in.alpha) && Convert(out.color, in.color);
     }
 
     bool Converter::Convert(wgpu::PrimitiveState& out, const interop::GPUPrimitiveState& in) {