Fix Incorrect Positioning

[masukomi]

Fix wrong positioning

Description:

• Fix wrong positioning caused by loading data and resizing dropdown after calculating position.

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Tasks:

• [x] Clear dropdown content when closing the dropdown

• [x] Resize the dropdown BEFORE positioning it

• [x] Sign change on a math operation

Example:

You can see that the search and drop down is disconnected from the pull-down. We have seen much more extreme examples of this disconnect.

Original work was by @DJA89

[argerim]

@masukomi Hello man pls create in https://github.com/select2/select2

[masukomi]

will do. closing.