[js] Fix 64bit integer literals

Author: pmurias

src/vm/js/Compiler.nqp

@@ -1417,7 +1417,7 @@ class QAST::CompilerJS does DWIMYNameMangling does SerializeOnce {
 
     multi method as_js(QAST::IVal $node, :$want) {
         if $want == $T_INT64 || $want == $T_UINT64 {
-            Chunk.new($want,'('~$node.value()~'n)', :$node);
+            Chunk.new($want,'nqp.BigInt("'~$node.value()~'")', :$node);
         } else {
             # TODO think about 64bit values
             Chunk.new($T_INT,'('~$node.value()~')', :$node);

src/vm/js/nqp-runtime/runtime.js

@@ -836,6 +836,7 @@ exports.createSourceMap = core.createSourceMap;
 exports.ZERO = JSBI.BigInt(0);
 exports.asIntN = asIntN.asIntN;
 exports.asUintN = asIntN.asUintN;
+exports.BigInt = JSBI.BigInt;
 
 module.exports.freshGlobalContext = globalContext.freshGlobalContext;
 module.exports.setGlobalContext = globalContext.setGlobalContext;