Prevent duplicate parameters in functions (#2177)
Prevent duplicate parameters in functions (#2177)

Prevents the coder from using duplicate parameters names in functions.

In the validator function check for parameter names that have been used. If it finds a block with a name that matches return null so that it will revert the change. Also change the name each time a new parameter is created to try to prevent duplicate name.
nickmain/blockly,twodee/blockly,google/blockly,picklesrus/blockly,google/blockly,nickmain/blockly,rachel-fenichel/blockly,nickmain/blockly,google/blockly,twodee/blockly,google/blockly,nickmain/blockly,rachel-fenichel/blockly,mark-friedman/blockly,google/blockly,joshlory/blockly,twodee/blockly,rachel-fenichel/blockly,picklesrus/blockly,twodee/blockly,nickmain/blockly,twodee/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,mark-friedman/blockly,rachel-fenichel/blockly,twodee/blockly,mark-friedman/blockly,rachel-fenichel/blockly,picklesrus/blockly,google/blockly,mark-friedman/blockly,joshlory/blockly,mark-friedman/blockly,google/blockly,mark-friedman/blockly,nickmain/blockly,joshlory/blockly