Here, i have attached the PDF, that PDF document contains "Nudi" as an embedded font. When i searching the particular word (that in Nudi font), the search result selecting the word that context next to the exact word.

Link to PDF file (or attach file here):
[sample_pdf.zip](https://github.com/mozilla/pdf.js/files/229582/sample_pdf.zip)

Configuration:
- Web browser and its version: Mozilla 45.0.2
- Operating system and its version: Windows 7
- PDF.js version: 1.4.20-disc

What is the expected behavior? (add screenshot)
![find_01](https://cloud.githubusercontent.com/assets/17423938/14704922/c2e67f2c-07d4-11e6-9320-9aed2578d377.png)

if (this._extractTextPromises.length > 0) {
      return;
    }
    let promise = Promise.resolve();
    for (let i = 0, ii = this._linkService.pagesCount; i < ii; i++) {
      const extractTextCapability = createPromiseCapability();
      this._extractTextPromises[i] = extractTextCapability.promise;
      promise = promise.then(() => {
        return this._pdfDocument
          .getPage(i + 1)
          .then(pdfPage => {
            return pdfPage.getTextContent({
              normalizeWhitespace: true,
            });
          })
          .then(
            textContent => {
              const textItems = textContent.items;
              const strBuf = [];
              for (let j = 0, jj = textItems.length; j < jj; j++) {
                strBuf.push(textItems[j].str);
              }
              
              this._pageContents[i] = normalize(strBuf.join(""));
              extractTextCapability.resolve(i);
            },
            reason => {
              console.error(