Override the z-index for the blocks drag layer. At 1000, it will be over everything in the gui other than the navbar itself (monitors on the stage, tutorials, alerts, dropdown menus, etc.)

It also avoids repeating the costly object spread, which becomes a problem for projects with a lot of sprites

Adds unit tests for this HOC.

Use PureComponent instead since it is a simple shouldComponentUpdate check now.

Forcing the playhead onto its own painting layer removes an expensive composite with the waveform. Animate using transforms instead of left prevents layouts of the rest of the page while playing a sound.

The waveform component was being re-rendered while the playhead changed, which is a costly operation because it has to calculate the full svg path data string.

Also use white as the background since it gives the same impact and will not look bad if the filter isn't applied or takes a while to be applied

See #4382 for more info about why, and what we need to follow up on it

The previous change that made the images laid out using absolute meant that the close button was layered below the sprite image, making it now clickable

On some projects, the sprite image changes frequently, which can cause global layouts and paints if we arent careful. Use the same absolute positioning strategy from the sprite library animations to contain layouts to the sprite image itself

Discovered this while trying to pass other props to the stage wrapper, we were not passing isRTL to the stage wrapper, causing ask/answer bubble to not display the right direction.

Move the onClick handler to the overlay wrapper so that the whole stage is clickable to start the project instead of just the green flag button

Browsers other than IE will be allowed to load the GUI.
However, if there is an error, the error boundary will display an unsupported browser message recommending they update to the latest version of a supported browser.

For the purposes of this PR, ‘supported’ means you can load the gui (anything other than IE), and recommended is just the browsers that meet our minimum requirements for Chrome, Firefox, Edge and Safari.

Fixes useability issue where the drop area was too small, and you couldn't see it.