Bars in bar graph appear in front of track

[KatieWoe]

Test device:
Dell Laptop
Operating System:
Windows 10
Browser:
Chrome and Edge
Problem description:
If tracks in the playground screen are laid over the energy bar graph they will appear in front of the axes, titles, and labels. However, it will appear behind the bars showing energy. The skater herself will appear in front of he bars showing energy. This is for phetsims/qa/issues/134
Steps to reproduce:

1. Go to the playground screen
2. Select the bar graph checkbox
3. Build a track that is in front of the graph (Easiest to see if built towards the bottom of the graph, so the bars don't need to be tall to reach it)
4. Start the skater down the track

Screenshots:

Troubleshooting information (do not edit):

Name: ‪Energy Skate Park: Basics‬ URL: https://phet-dev.colorado.edu/html/energy-skate-park-basics/1.4.0-dev.1/phet/energy-skate-park-basics_en_phet.html Version: 1.4.0-dev.1 2018-06-20 00:09:06 UTC Flags: pixelRatioScaling User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36 Language: en-US Window: 1536x741 Pixel Ratio: 2.5/1 WebGL: WebGL 1.0 (OpenGL ES 2.0 Chromium) GLSL: WebGL GLSL ES 1.0 (OpenGL ES GLSL ES 1.0 Chromium) Vendor: WebKit (WebKit WebGL) Vertex: attribs: 16 varying: 30 uniform: 4096 Texture: size: 16384 imageUnits: 16 (vertex: 16, combined: 32) Max viewport: 16384x16384 OES_texture_float: true Dependencies JSON: {"assert":{"sha":"928741cf","branch":"master"},"axon":{"sha":"f0522e7c","branch":"master"},"brand":{"sha":"89d28f63","branch":"master"},"chipper":{"sha":"e8946524","branch":"master"},"dot":{"sha":"6482f8c9","branch":"master"},"energy-skate-park-basics":{"sha":"288fcefd","branch":"master"},"joist":{"sha":"22e437d5","branch":"master"},"kite":{"sha":"a1086efc","branch":"master"},"phet-core":{"sha":"17326041","branch":"master"},"phet-io":{"sha":"3ea0727a","branch":"master"},"phet-io-wrapper-classroom-activity":{"sha":"53708616","branch":"master"},"phet-io-wrapper-hookes-law-energy":{"sha":"8a546a32","branch":"master"},"phet-io-wrapper-lab-book":{"sha":"1527afd6","branch":"master"},"phet-io-wrappers":{"sha":"8d814eab","branch":"master"},"phetcommon":{"sha":"6ec8cd89","branch":"master"},"query-string-machine":{"sha":"4182612f","branch":"master"},"scenery":{"sha":"88cb642e","branch":"master"},"scenery-phet":{"sha":"7bcde0b2","branch":"master"},"sherpa":{"sha":"88c3b828","branch":"master"},"sun":{"sha":"7579e8fa","branch":"master"},"tandem":{"sha":"8461b6f3","branch":"master"}}

[jessegreenberg]

Thanks @KatieWoe, fixed with the above commit:

[jessegreenberg]

Reopening, @phet-steele mentioned this layering was intentional because of #295.

[jessegreenberg]

Lets pick this up in #295 since this issue is a duplicate of that one.

[jessegreenberg]

This is no longer true since WebGL is being removed in phetsims/energy-skate-park#66 and we no longer need the layering to support that.