Make the argument to init optional in the Typescript declaration too

Commit 8ace828 made the argument to the
generated init() function optional (when the target is "web"), but it is still
marked as required in the generated .d.ts file.

Fix the generated declaration to match the function definition again.

crates/cli-support/src/js/mod.rs

@@ -396,7 +396,7 @@ impl<'a> Context<'a> {
         Ok(imports)
     }
 
-    fn ts_for_init_fn(has_memory: bool) -> String {
+    fn ts_for_init_fn(has_memory: bool, has_module_or_path_optional: bool) -> String {
         let (memory_doc, memory_param) = if has_memory {
             (
                 "* @param {WebAssembly.Memory} maybe_memory\n",
@@ -405,6 +405,7 @@ impl<'a> Context<'a> {
         } else {
             ("", "")
         };
+        let arg_optional = if has_module_or_path_optional { "?" } else { "" };
         format!(
             "\n\
             /**\n\
@@ -417,9 +418,9 @@ impl<'a> Context<'a> {
             * @returns {{Promise<any>}}\n\
             */\n\
             export default function init \
-                (module_or_path: RequestInfo | BufferSource | WebAssembly.Module{}): Promise<any>;
+                (module_or_path{}: RequestInfo | BufferSource | WebAssembly.Module{}): Promise<any>;
         ",
-            memory_doc, memory_param
+            memory_doc, arg_optional, memory_param
         )
     }
 
@@ -461,7 +462,7 @@ impl<'a> Context<'a> {
             _ => "",
         };
 
-        let ts = Self::ts_for_init_fn(mem.import.is_some());
+        let ts = Self::ts_for_init_fn(mem.import.is_some(), !default_module_path.is_empty());
 
         // Initialize the `imports` object for all import definitions that we're
         // directed to wire up.