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/samples/compute_boids.wgsl.expected.glsl

@@ -23,6 +23,18 @@ struct Particle {
   vec2 pos;
   vec2 vel;
 };
+struct SimParams {
+  float deltaT;
+  float rule1Distance;
+  float rule2Distance;
+  float rule3Distance;
+  float rule1Scale;
+  float rule2Scale;
+  float rule3Scale;
+};
+struct Particles {
+  Particle particles[5];
+};
 struct tint_symbol_6 {
   uvec3 tint_symbol;
 };
@@ -71,6 +83,18 @@ struct Particle {
   vec2 pos;
   vec2 vel;
 };
+struct SimParams {
+  float deltaT;
+  float rule1Distance;
+  float rule2Distance;
+  float rule3Distance;
+  float rule1Scale;
+  float rule2Scale;
+  float rule3Scale;
+};
+struct Particles {
+  Particle particles[5];
+};
 struct tint_symbol_6 {
   uvec3 tint_symbol;
 };
@@ -107,6 +131,18 @@ struct Particle {
   vec2 pos;
   vec2 vel;
 };
+struct SimParams {
+  float deltaT;
+  float rule1Distance;
+  float rule2Distance;
+  float rule3Distance;
+  float rule1Scale;
+  float rule2Scale;
+  float rule3Scale;
+};
+struct Particles {
+  Particle particles[5];
+};
 
 layout (binding = 0) uniform SimParams_1 {
   float deltaT;

test/samples/cube.wgsl.expected.glsl

@@ -1,6 +1,9 @@
 #version 310 es
 precision mediump float;
 
+struct Uniforms {
+  mat4 modelViewProjectionMatrix;
+};
 
 layout (binding = 0) uniform Uniforms_1 {
   mat4 modelViewProjectionMatrix;
@@ -63,6 +66,9 @@ void main() {
 #version 310 es
 precision mediump float;
 
+struct Uniforms {
+  mat4 modelViewProjectionMatrix;
+};
 struct VertexInput {
   vec4 cur_position;
   vec4 color;