[wasm][asm.js] Fix and enable several asm.js tests with the new parser.

test/mjsunit/wasm/embenchen/copy.js

 // Modified embenchen to direct to asm-wasm.
-// Flags: --validate-asm --allow-natives-syntax
+// Flags: --validate-asm --allow-natives-syntax --fast-validate-asm
 
 var EXPECTED_OUTPUT = 'sum:8930\n';
 var Module = {
   arguments: [1],
   print: function(x) {Module.printBuffer += x + '\n';},
   preRun: [function() {Module.printBuffer = ''}],
   postRun: [function() {
     assertEquals(EXPECTED_OUTPUT, Module.printBuffer);
   }],
 };
@@ skipping 5959 matching lines @@
 }
 
 // shouldRunNow refers to calling main(), not run().
 var shouldRunNow = true;
 if (Module['noInitialRun']) {
   shouldRunNow = false;
 }
 
 
 run([].concat(Module["arguments"]));