fix single line comment before props (#531)

#530
prevent `// comment` being treat as props docstring

Author: jasonlyu123

packages/svelte2tsx/src/svelte2tsx/nodes/ExportedNames.ts

@@ -53,7 +53,10 @@ export class ExportedNames
             const comment = ts.getLeadingCommentRanges(fileText, exportExpr.getFullStart());
 
             if (comment) {
-                doc = fileText.substring(comment[0].pos, comment[0].end);
+                const [first] = comment;
+                if (first?.kind === ts.SyntaxKind.MultiLineCommentTrivia) {
+                    doc = fileText.substring(first.pos, first.end);
+                }
             }
         }
 

packages/svelte2tsx/test/svelte2tsx/samples/ts-export-doc/expected.tsx

@@ -10,15 +10,18 @@
      */
      let b = 1;
      let c;
+
+    // not this one
+     let d;
 ;
 () => (<></>);
-return { props: {a: a , b: b , c: c} as {
+return { props: {a: a , b: b , c: c , d: d} as {
 /**
      * DOCS!
      */a: string, 
 /**
      * MORE DOCS!
-     */b?: typeof b, c: typeof c}, slots: {}, getters: {}, events: {} }}
+     */b?: typeof b, c: typeof c, d: typeof d}, slots: {}, getters: {}, events: {} }}
 
 export default class Input__SvelteComponent_ extends createSvelte2TsxComponent(__sveltets_partial(__sveltets_with_any_event(render))) {
-}
+}

packages/svelte2tsx/test/svelte2tsx/samples/ts-export-doc/input.svelte

@@ -8,4 +8,7 @@
      */
     export let b = 1;
     export let c;
+
+    // not this one
+    export let d;
 </script>