Update lang-fr.js
Update lang-fr.js

Correction of a mistranslation lines 438
"repeat until" is "répéter jusqu'à" in french,

"répéter indéfiniment si" is "forever if" in french
ericrosenbaum/BeetleBlocks,ericrosenbaum/BeetleBlocks,jmoenig/Snap--Build-Your-Own-Blocks,jmoenig/Snap--Build-Your-Own-Blocks