text: Title: Screenshot Quality argument not working?
  Body: The quality argument in coroutine screenshot is not working well 
  
  The code i tested with 
  ```
   browser = await launch(
              headless=True,
              executablePath=EXEC_PATH
              )
  page = await browser.newPage()
  await page.goto(link)
  await page.screenshot({'fullPage': True, 'path': './FILES/584512526/3726/Python Dictionarieswebshotbot.jpeg', 'type': 'jpeg', 'quality': 1})
  ```
  
  Unfortunately the output quality is same if i change the quality argv to 100
  Below is an example of a screenshot taken with quality 1
  
  ![alenpaul2001 (AlenPaulVarghese) · GitHub-webshotbot (6)](https://user-images.githubusercontent.com/38587581/83202629-9b731200-a165-11ea-928c-8fb52636b53f.JPEG)
  
  **Is there something wrong with my code**
  