Remove loop and ExactSizeIterator from ShaderDefIterator

Author: MinerSebas

crates/bevy_render/src/shader/shader_defs.rs

@@ -48,24 +48,10 @@ impl<'a> Iterator for ShaderDefIterator<'a> {
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        let mut index = 0;
-        let mut size = 0;
-
-        loop {
-            if index == self.shader_defs.shader_defs_len() {
-                return (size, Some(size));
-            }
-
-            if self.shader_defs.get_shader_def(index).is_some() {
-                size += 1;
-            }
-            index += 1;
-        }
+        (0, Some(self.shader_defs.shader_defs_len()))
     }
 }
 
-impl<'a> ExactSizeIterator for ShaderDefIterator<'a> {}
-
 impl ShaderDef for bool {
     fn is_defined(&self) -> bool {
         *self