Roll chromium to r486981. (#87)

This patch rolls chromium to r486981 and prepares
for the introduction of device emulation.

test/test.js

@@ -221,7 +221,7 @@ describe('Puppeteer', function() {
         await page.waitFor('*');
         fail('Failed waitFor did not throw.');
       } catch (e) {
-        expect(e.message).toBe('Evaluation failed: document.querySelector is not a function');
+        expect(e.message).toContain('Evaluation failed: document.querySelector is not a function');
       }
     }));
   });