[turbofan] re-enable some tests for arm64.

Those tests were disabled because of an issue in TruncateDoubleToI which has
been fixed since.

BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/605253002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24371 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/cctest/compiler/test-simplified-lowering.cc

@@ -56,8 +56,6 @@ class SimplifiedLoweringTester : public GraphBuilderTester<ReturnType> {
 };
 
 
-#ifndef V8_TARGET_ARCH_ARM64
-// TODO(titzer): these result in a stub call that doesn't work on ARM64.
 // TODO(titzer): factor these tests out to test-run-simplifiedops.cc.
 // TODO(titzer): test tagged representation for input to NumberToInt32.
 TEST(RunNumberToInt32_float64) {
@@ -113,7 +111,6 @@ TEST(RunNumberToUint32_float64) {
     }
   }
 }
-#endif
 
 
 // Create a simple JSObject with a unique map.