clear pixel info when content changes/etc
clear pixel info when content changes/etc

cedricpinson/WebGL-Inspector,cedricpinson/WebGL-Inspector,greggman/WebGL-Inspector,TheKK/WebGL-Inspector,cedricpinson/WebGL-Inspector,TheKK/WebGL-Inspector,benvanik/WebGL-Inspector,TheKK/WebGL-Inspector,mcanthony/WebGL-Inspector,greggman/WebGL-Inspector,mcanthony/WebGL-Inspector,benvanik/WebGL-Inspector,greggman/WebGL-Inspector,mcanthony/WebGL-Inspector,benvanik/WebGL-Inspector