Fix: Temporary disableFontFaces on IOS 10.3

-temp fix until mozilla/pdf.js#8267 is resolved

src/lib/Browser.js

@@ -255,6 +255,15 @@ class Browser {
     static isAndroid() {
         return /Android/g.test(navigator.userAgent);
     }
+
+    /**
+     * Returns whether or not the device is running IOS 10.3.X that has Font Ligature rendering issue.
+     *
+     * @return {boolean} True if device is running IOS 10.3.x
+     */
+    static isIOSWithFontIssue() {
+        return Browser.isIOS() && /(?:OS\s)10_3/i.test(navigator.userAgent);
+    }
 }
 
 export default Browser;

src/lib/viewers/doc/DocBaseViewer.js

@@ -589,6 +589,10 @@ class DocBaseViewer extends BaseViewer {
             enhanceTextSelection: true // improves text selection if true
         });
 
+        // Disable font faces on IOS 10.3.X
+        // @NOTE(JustinHoldstock) 2017-04-11: Check to remove this after next IOS release after 10.3.1
+        PDFJS.disableFontFace = PDFJS.disableFontFace || Browser.isIOSWithFontIssue();
+
         // Use chunk size set in viewer options if available
         let rangeChunkSize = this.getViewerOption('rangeChunkSize');
 

src/lib/viewers/doc/__tests__/DocBaseViewer-test.js

@@ -1004,6 +1004,27 @@ describe('src/lib/viewers/doc/DocBaseViewer', () => {
                 expect(stubs.pdfViewer.linkService.setDocument).to.be.called;
             });
         });
+
+        // @NOTE(JustinHoldstock) 2017-04-11: Check to remove this after next IOS release after 10.3.1
+        it('should test user agent if on Safari Mobile for IOS 10.3', () => {
+            const doc = {
+                url: 'url'
+            };
+            sandbox.stub(PDFJS, 'getDocument').returns(Promise.resolve(doc));
+            sandbox.stub(docBase, 'getViewerOption').returns(100);
+            docBase.options.location = {
+                locale: 'en-US'
+            };
+
+            const getStub = sandbox.stub(Browser, 'isIOSWithFontIssue').returns(true);
+
+            docBase.initViewer('url');
+
+            // Mobile stub cannot be called if get stub is never called.
+            // See note for this test, for more info.
+            expect(getStub).to.be.called;
+            expect(PDFJS.disableFontFace).to.be.true;
+        });
     });
 
     describe('setupPdfjs()', () => {