test: Add test cases for zero value constructors

Fixed: tint:477
Change-Id: I087c24904ab2f38524ab2c39092fbfb277fdba3b
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/55256
Auto-Submit: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
Commit-Queue: Ben Clayton <bclayton@google.com>
diff --git a/test/expressions/zero_init/struct/array.wgsl b/test/expressions/zero_init/struct/array.wgsl
new file mode 100644
index 0000000..148b457
--- /dev/null
+++ b/test/expressions/zero_init/struct/array.wgsl
@@ -0,0 +1,7 @@
+struct S {
+    a : array<f32, 4>;
+};
+
+fn f() {
+    var v = S();
+}