Windows 7 - caption buttons don't scale properly

[bsclifton]

Did you search for similar issues before submitting this one?
Yes

Describe the issue you encountered:
On Windows 7, the caption buttons (min/max/close) buttons in the top right look OK at 100% DPI. However, when scaled up to 125%, 150%, etc the restorre button looks bad. This can be correct by using SVGs (the close button is already an SVG).

Expected behavior:
Bitmaps match native at that resolution

• Platform (Win7, 8, 10? macOS? Linux distro?):
  Windows 7
• Brave Version:
  0.12.3
• Screenshot if needed:
  
• Any related issues:
  The Windows 10 version of this issue was fixed w/ Redid caption buttons for Windows 10 using SVG #4560

[bsclifton]

Closing since this will be fixed when we move to Brave Core