Update `tint` to use new single entry point path for GLSL

Move the GLSL emission over to the new single entry point path and
remove the custom GLSL code for enforcing single entry point.

Bug: 380043961
Change-Id: I3bfe80b1c6d046c2ecaec52514d245f4c4e48d3e
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/218316
Reviewed-by: James Price <jrprice@google.com>
Commit-Queue: James Price <jrprice@google.com>
diff --git a/test/tint/builtins/gen/var/textureLoad/374351.wgsl.expected.glsl b/test/tint/builtins/gen/var/textureLoad/374351.wgsl.expected.glsl
index 8cf618a..b5580e6 100644
--- a/test/tint/builtins/gen/var/textureLoad/374351.wgsl.expected.glsl
+++ b/test/tint/builtins/gen/var/textureLoad/374351.wgsl.expected.glsl
@@ -1,3 +1,6 @@
+//
+// fragment_main
+//
 #version 310 es
 precision highp float;
 precision highp int;
@@ -16,6 +19,9 @@
 void main() {
   v.inner = textureLoad_374351();
 }
+//
+// compute_main
+//
 #version 310 es
 
 layout(binding = 0, std430)
@@ -33,6 +39,9 @@
 void main() {
   v.inner = textureLoad_374351();
 }
+//
+// vertex_main
+//
 #version 310 es