Fix search in pdf a containing some UTF-32 characters (bug 1820909)

Some chars were supposed to have a length equals to 1 but UTF-32 chars
can be longuer.

test/pdfs/.gitignore

@@ -576,3 +576,4 @@
 !bug1770750.pdf
 !issue16063.pdf
 !issue16067.pdf
+!bug1820909.1.pdf

test/pdfs/bug1820909.pdf.link

@@ -0,0 +1,2 @@
+https://web.archive.org/web/20221122204959/https://www.unicode.org/charts/PDF/U31350.pdf
+

test/test_manifest.json

@@ -7455,5 +7455,12 @@
       "rounds": 1,
       "link": true,
       "type": "eq"
+   },
+   {
+      "id": "bug1820909",
+      "file": "pdfs/bug1820909.pdf",
+      "md5": "d95a83a868671a03cbf322f16b2e2b9d",
+      "link": true,
+      "type": "other"
    }
 ]

test/unit/pdf_find_controller_spec.js

@@ -854,4 +854,50 @@ describe("pdf_find_controller", function () {
       pageMatchesLength: [[7]],
     });
   });
+
+  it("performs a search in a text with some UTF-32 chars", async function () {
+    if (isNodeJS) {
+      pending("Linked test-cases are not supported in Node.js.");
+    }
+
+    const { eventBus, pdfFindController } = await initPdfFindController(
+      "bug1820909.pdf"
+    );
+
+    await testSearch({
+      eventBus,
+      pdfFindController,
+      state: {
+        query: "31350",
+      },
+      matchesPerPage: [1, 2],
+      selectedMatch: {
+        pageIndex: 0,
+        matchIndex: 0,
+      },
+      pageMatches: [[41], [131, 1359]],
+      pageMatchesLength: [[5], [5, 5]],
+    });
+  });
+
+  it("performs a search in a text with some UTF-32 chars followed by a dash at the end of a line", async function () {
+    const { eventBus, pdfFindController } = await initPdfFindController(
+      "bug1820909.1.pdf"
+    );
+
+    await testSearch({
+      eventBus,
+      pdfFindController,
+      state: {
+        query: "abcde",
+      },
+      matchesPerPage: [2],
+      selectedMatch: {
+        pageIndex: 0,
+        matchIndex: 0,
+      },
+      pageMatches: [[42, 95]],
+      pageMatchesLength: [[5, 5]],
+    });
+  });
 });