#54: this.dispatchEvent(UPDATE) called too often (closes #54)

[FrancescoCioria]

Closes #54

Test Plan

tests performed

tested in Chrome, Safari 10 and IE11:

• every example still works correctly
• improve first example to programmatically change value to a long one after some seconds
  • it updates correctly

tests not performed (domain coverage)

At times not everything can be tested, and writing what hasn't been tested is just as important as writing what has been tested.

An example of partial test is a field displaying 4 possible values. If 3 values are tested, with screenshots, and 1 is not, then it should be mentioned here.}

[nemobot]