deps: update ChakraCore to chakra-core/ChakraCore@c6d73ba949

[MERGE #4494 @obastemur] Enable sharedarray ft. for 262 testing

Merge pull request #4494 from obastemur:add_enableshared_262

Reviewed-By: chakrabot <chakrabot@users.noreply.github.com>

Author: obastemur

deps/chakrashim/core/test/262/rlexe.xml

@@ -2,7 +2,7 @@
 <regress-exe>
   <test>
     <default>
-      <compile-flags>-Test262</compile-flags>
+      <compile-flags>-ESSharedArrayBuffer -Test262</compile-flags>
       <files>262test.js</files>
     </default>
   </test>