Add back dir property in spans in text layer

- aims to fix #12909

src/display/text_layer.js

@@ -113,6 +113,9 @@ const renderTextLayer = (function renderTextLayerClosure() {
     textDiv.style.fontFamily = style.fontFamily;
 
     textDiv.textContent = geom.str;
+    // geom.dir may be 'ttb' for vertical texts.
+    textDiv.dir = geom.dir;
+
     // `fontName` is only used by the FontInspector, and we only use `dataset`
     // here to make the font name available in the debugger.
     if (task._fontInspectorEnabled) {

test/pdfs/issue12909.pdf.link

@@ -0,0 +1 @@
+https://web.archive.org/web/20210126084513/https://www.machonso.org/uploads/images/%D7%95%D7%95%D7%9C%D7%A3.pdf

test/test_manifest.json

@@ -4526,6 +4526,14 @@
        "link": false,
        "type": "eq"
     },
+    {  "id": "issue12909",
+       "file": "pdfs/issue12909.pdf",
+       "md5": "0faa1cb029c3323c168595cccbe46ec0",
+       "link": true,
+       "rounds": 1,
+       "lastPage": 1,
+       "type": "text"
+    },
     {  "id": "issue5592",
        "file": "pdfs/issue5592.pdf",
        "md5": "a0750f95afa80c880f7966df7062616c",