glsl: Always emit structures

Skipping those that are block-decorated is not correct, as
block-decorated structures can also have non-buffer usages. This is
even clearer now that WGSL has removed the block attribute.

Bug: tint:1324
Change-Id: I6484766a5c541d39e2dc08beb3ae7b889759a3fb
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/72083
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>

test/buffer/storage/static_index/read.wgsl.expected.glsl

@@ -7,6 +7,18 @@ struct Inner {
 struct tint_padded_array_element {
   Inner el;
 };
+struct S {
+  ivec3 a;
+  int b;
+  uvec3 c;
+  uint d;
+  vec3 e;
+  float f;
+  mat2x3 g;
+  mat3x2 h;
+  Inner i;
+  tint_padded_array_element j[4];
+};
 
 layout (binding = 0) buffer S_1 {
   ivec3 a;

test/buffer/storage/static_index/write.wgsl.expected.glsl

@@ -7,6 +7,18 @@ struct Inner {
 struct tint_padded_array_element {
   Inner el;
 };
+struct S {
+  ivec3 a;
+  int b;
+  uvec3 c;
+  uint d;
+  vec3 e;
+  float f;
+  mat2x3 g;
+  mat3x2 h;
+  Inner i;
+  tint_padded_array_element j[4];
+};
 
 layout (binding = 0) buffer S_1 {
   ivec3 a;

test/buffer/uniform/dynamic_index/read.wgsl.expected.glsl

@@ -14,6 +14,9 @@ struct Inner {
   mat3x2 j;
   ivec4 k[4];
 };
+struct S {
+  Inner arr[8];
+};
 
 layout (binding = 0) uniform S_1 {
   Inner arr[8];

test/buffer/uniform/static_index/read.wgsl.expected.glsl

@@ -7,6 +7,20 @@ struct Inner {
 struct tint_padded_array_element {
   Inner el;
 };
+struct S {
+  ivec3 a;
+  int b;
+  uvec3 c;
+  uint d;
+  vec3 e;
+  float f;
+  ivec2 g;
+  ivec2 h;
+  mat2x3 i;
+  mat3x2 j;
+  Inner k;
+  tint_padded_array_element l[4];
+};
 
 layout (binding = 0) uniform S_1 {
   ivec3 a;