Update test/tint/array to store results

This CL updates the `test/tint/array` tests to make sure the results
are stored back into a storage variable. Also make sure each test has
an entry point.

Change-Id: I8a87129c22ed56bdbcecf69464aa03e9ce387659
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/164580
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: dan sinclair <dsinclair@chromium.org>
diff --git a/test/tint/array/function_parameter.wgsl.expected.wgsl b/test/tint/array/function_parameter.wgsl.expected.wgsl
index be06c51..9305ffe 100644
--- a/test/tint/array/function_parameter.wgsl.expected.wgsl
+++ b/test/tint/array/function_parameter.wgsl.expected.wgsl
@@ -1,3 +1,5 @@
+@group(0) @binding(0) var<storage, read_write> s : f32;
+
 fn f1(a : array<f32, 4>) -> f32 {
   return a[3];
 }
@@ -18,4 +20,5 @@
   let v1 : f32 = f1(a1);
   let v2 : f32 = f2(a2);
   let v3 : f32 = f3(a3);
+  s = ((v1 + v2) + v3);
 }