Nice test prototype! I managed to make it to the end of the level :)
Positives:
The WebGL works well and is smooth.
Movement physics is good and accurate.
Level design is good (It made me want to keep trying till I completed it :)
Suggestions:
The collision detection needs a little work. The square can go half-way into the triangle before collision is detected.
Overall, though great start and I look forward to seeing more!