Fixed a ShaderGraph issue where the right click menu doesn't work whe…

[joshua-davis]

…n a stack block node is selected. Fixes fogbugz 1320212.

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Purpose of this PR

Fixing https://fogbugz.unity3d.com/f/cases/1320212/

The root issue was the logic to check for and handle floating block nodes was preventing the right click context menus. To get around this, I fixed block node resetting to only operate on floating blocks (one's whose parent wasn't the context view).

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Testing status

• Select a block node then right-click on the graph in empty space. A context menu appears.
• Select multiple block nodes then right-click on the graph in empty space. A context menu appears.
• Select a non block node then right-click on the graph in empty space. A context menu appears.
• Select a block node and drag it out. While still dragging middle click. The block nodes should go back into the stack. (This is what the code I had to fix was for).
• Select a block node and drag it out. While still dragging right click. The block nodes should go back into the stack and no right-click menu appears.

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Comments to reviewers

Notes for the reviewers you have assigned.

[jessebarker]

LGTM

[ghost]

Did a bit of testing around stack nodes making sure things still work correctly. Looks good!

[esmelusina]

Looks good.