Reproduction steps:
1) Open "798493 WebGL Input" project and build it for WebGL
2) Launch built project
3) Press space button, right/left arrow keys or left mouse button; notice GUI Text changes
4) Press and hold space button and press somewhere outside game window (for example on desktop or change focus to any other application)
5) Release pressed button
6) Go back to game window

Expected result:
Button should be detected as unpressed.

Actual result:
Button detected as pressed and gets updated only when you press that button again.

Note:
This also reproduces on Web Player.