Hotfix printing italicized text in Chrome

If browser is Chrome, and version < 82, then remove all italics on page before printing.
See #38 for further context.

VERSION

@@ -1 +1 @@
-1.1.0
+1.1.1

src_js/NodeManager.ts

@@ -92,6 +92,29 @@ export default class NodeManager {
     });
   }
 
+  /**
+   * HACK: Toggles italics in Chrome before printing.
+   * (See issue eecs485staff/primer-spec#38)
+   * @param isItalicsEnabled boolean indicating whether italics should be enabled
+   */
+  _toggleItalicsInChrome(isItalicsEnabled: boolean) {
+    const chromeVersion = Utilities.getChromeVersion();
+    if (chromeVersion === false || chromeVersion >= 82) {
+      return;
+    }
+
+    const all_italic_els =
+      'em, dfn, .text-italic, dt, .highlight .cm, .highlight .c1, ' +
+      '.highlight .cs, .highlight .cd, .highlight .ge, .primer-spec-toc-h4';
+    const font_style = isItalicsEnabled ? 'italic' : 'inherit';
+
+    const nodes: NodeListOf<HTMLElement> =
+      document.querySelectorAll(all_italic_els);
+    Array.from(nodes).map(el => {
+      el.style.fontStyle = font_style;
+    });
+  }
+
   /**
    * Register handler when page is previewed for printing. The handler hides
    * the sidebar and settings panes and restores them after the print preview
@@ -111,6 +134,7 @@ export default class NodeManager {
         should_undo_settings_toggle = true;
         this.settings.toggle();
       }
+      this._toggleItalicsInChrome(false);
     };
     const afterPrint = () => {
       if (should_undo_sidebar_toggle) {
@@ -121,6 +145,7 @@ export default class NodeManager {
         should_undo_settings_toggle = false;
         this.settings.toggle();
       }
+      this._toggleItalicsInChrome(true);
     };
     // Safari doesn't support onbeforeprint, etc.
     // So this is the "official" work-around for webkit.

src_js/Utilities.ts

@@ -9,4 +9,14 @@ export default class Utilities {
   static isSmallScreen() {
     return document.documentElement.clientWidth < 900;
   }
+
+  /**
+   * Return a number indicating the Chrome major version. Returns false if
+   * not Chrome.
+   */
+  static getChromeVersion () {
+    // Based on: https://stackoverflow.com/a/4900484/5868796
+    const raw = navigator.userAgent.match(/Chrom(e|ium)\/([0-9]+)\./);
+    return raw ? parseInt(raw[2], 10) : false;
+  }
 }