wgsl: Replace [[decoration]] with @decoration

Deprecate the old syntax. Migrate everything to the new syntax.

Bug: tint:1382
Change-Id: Ide12b2e927b17dc93b9714c7049090864cc568d3
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/77260
Reviewed-by: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>
Commit-Queue: David Neto <dneto@google.com>

test/access/let/matrix.spvasm.expected.wgsl

@@ -3,7 +3,7 @@ fn main_1() {
   return;
 }
 
-[[stage(compute), workgroup_size(1, 1, 1)]]
+@stage(compute) @workgroup_size(1, 1, 1)
 fn main() {
   main_1();
 }

test/access/let/matrix.wgsl

@@ -1,4 +1,4 @@
-[[stage(compute), workgroup_size(1)]]
+@stage(compute) @workgroup_size(1)
 fn main() {
   let m : mat3x3<f32> = mat3x3<f32>(vec3<f32>(1., 2., 3.), vec3<f32>(4., 5., 6.), vec3<f32>(7., 8., 9.));
   let v : vec3<f32> = m[1];

test/access/let/matrix.wgsl.expected.wgsl

@@ -1,4 +1,4 @@
-[[stage(compute), workgroup_size(1)]]
+@stage(compute) @workgroup_size(1)
 fn main() {
   let m : mat3x3<f32> = mat3x3<f32>(vec3<f32>(1.0, 2.0, 3.0), vec3<f32>(4.0, 5.0, 6.0), vec3<f32>(7.0, 8.0, 9.0));
   let v : vec3<f32> = m[1];

test/access/let/vector.spvasm.expected.wgsl

@@ -5,7 +5,7 @@ fn main_1() {
   return;
 }
 
-[[stage(compute), workgroup_size(1, 1, 1)]]
+@stage(compute) @workgroup_size(1, 1, 1)
 fn main() {
   main_1();
 }

test/access/let/vector.wgsl

@@ -1,4 +1,4 @@
-[[stage(compute), workgroup_size(1)]]
+@stage(compute) @workgroup_size(1)
 fn main() {
   let v : vec3<f32> = vec3<f32>(1., 2., 3.);
   let scalar : f32 = v.y;

test/access/let/vector.wgsl.expected.wgsl

@@ -1,4 +1,4 @@
-[[stage(compute), workgroup_size(1)]]
+@stage(compute) @workgroup_size(1)
 fn main() {
   let v : vec3<f32> = vec3<f32>(1.0, 2.0, 3.0);
   let scalar : f32 = v.y;

test/access/var/matrix.spvasm.expected.wgsl

@@ -5,7 +5,7 @@ fn main_1() {
   return;
 }
 
-[[stage(compute), workgroup_size(1, 1, 1)]]
+@stage(compute) @workgroup_size(1, 1, 1)
 fn main() {
   main_1();
 }

test/access/var/matrix.wgsl

@@ -1,4 +1,4 @@
-[[stage(compute), workgroup_size(1)]]
+@stage(compute) @workgroup_size(1)
 fn main() {
   var m : mat3x3<f32>;
   let v : vec3<f32> = m[1];

test/access/var/matrix.wgsl.expected.wgsl

@@ -1,4 +1,4 @@
-[[stage(compute), workgroup_size(1)]]
+@stage(compute) @workgroup_size(1)
 fn main() {
   var m : mat3x3<f32>;
   let v : vec3<f32> = m[1];

test/access/var/vector.spvasm.expected.wgsl

@@ -8,7 +8,7 @@ fn main_1() {
   return;
 }
 
-[[stage(compute), workgroup_size(1, 1, 1)]]
+@stage(compute) @workgroup_size(1, 1, 1)
 fn main() {
   main_1();
 }

test/access/var/vector.wgsl

@@ -1,4 +1,4 @@
-[[stage(compute), workgroup_size(1)]]
+@stage(compute) @workgroup_size(1)
 fn main() {
   var v : vec3<f32>;
   let scalar : f32 = v.y;

test/access/var/vector.wgsl.expected.wgsl

@@ -1,4 +1,4 @@
-[[stage(compute), workgroup_size(1)]]
+@stage(compute) @workgroup_size(1)
 fn main() {
   var v : vec3<f32>;
   let scalar : f32 = v.y;