Enable dex2oat swap test for CC on x86.

The test should be OK after
    https://android-review.googlesource.com/335763

Test: m ART_USE_READ_BARRIER=true test-art-host-gtest
Bug: 29259363
Change-Id: I16f4051036b247b4f520533e77eaa71d6ff7bb41
diff --git a/dex2oat/dex2oat_test.cc b/dex2oat/dex2oat_test.cc
index 90b4955..e208337 100644
--- a/dex2oat/dex2oat_test.cc
+++ b/dex2oat/dex2oat_test.cc
@@ -399,11 +399,6 @@
 };
 
 TEST_F(Dex2oatSwapUseTest, CheckSwapUsage) {
-  // The `native_alloc_2_ >= native_alloc_1_` assertion below may not
-  // hold true on some x86 systems when read barriers are enabled;
-  // disable this test while we investigate (b/29259363).
-  TEST_DISABLED_FOR_READ_BARRIER_ON_X86();
-
   RunTest(false /* use_fd */,
           false /* expect_use */);
   GrabResult1();
diff --git a/runtime/common_runtime_test.h b/runtime/common_runtime_test.h
index 17e3729..26ec364 100644
--- a/runtime/common_runtime_test.h
+++ b/runtime/common_runtime_test.h
@@ -223,12 +223,6 @@
     return; \
   }
 
-#define TEST_DISABLED_FOR_READ_BARRIER_ON_X86() \
-  if (kUseReadBarrier && kRuntimeISA == kX86) { \
-    printf("WARNING: TEST DISABLED FOR READ BARRIER ON X86\n"); \
-    return; \
-  }
-
 #define TEST_DISABLED_FOR_STRING_COMPRESSION() \
   if (mirror::kUseStringCompression) { \
     printf("WARNING: TEST DISABLED FOR STRING COMPRESSION\n"); \