Atoms being returned from off of the play area do not repel existing molecules on the play area

[loganbraywork]

Test device
Windows 10 Laptop
Operating System
Windows 10
Browser
Chrome
Problem description
For phetsims/qa#459

Atoms which cannot bond with an existing molecule will normally repel the molecule if placed near it. This behavior does not occur when an atom is being returned from off of the play area to the play area, leading to overlap.
Steps to reproduce

1. Enter the Multiple screen
2. Create water
3. Move water molecule to the edge of the play area
4. Drag an oxygen atom off of the play area relatively close to the water molecule
   Visuals
   

Troubleshooting information:
!!!!! DO NOT EDIT !!!!!
Name: ‪Build a Molecule‬
URL: https://phet-dev.colorado.edu/html/build-a-molecule/0.0.0-dev.23/phet/build-a-molecule_all_phet.html
Version: 0.0.0-dev.23 2019-11-20 23:29:39 UTC
Features missing: generatedcontent, touch
Flags: pixelRatioScaling
User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.97 Safari/537.36
Language: en-US
Window: 1536x754
Pixel Ratio: 1.25/1
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: 4095
Texture: size: 16384 imageUnits: 16 (vertex: 16, combined: 32)
Max viewport: 32767x32767
OES_texture_float: true
Dependencies JSON: {}

[Denz1994]

The CollectionLayout includes the appropriate bounds for the play area. After the collection layout is responsible for the bounds the molecules can be contained inside of when separating (see Kit.separateMoleculeDestinations()). The correction here is that the play area bounds and separation bounds are now using the collection layout's bounds.

Can you confirm this isn't an issue in this dev version @KatieWoe?

[loganbraywork]

Appears to be fixed

[Denz1994]

Nice. Closing.