Revert "Disable some image_test cases with concurrent collector."

This reverts commit d52765768b634c6f32a9bddd5c1269f26d32ea3a.

Bug: 27578460
Change-Id: Ie23877ac5332e05805c251749159e8f00af4ac8c
diff --git a/compiler/image_test.cc b/compiler/image_test.cc
index 7779e44..91579e9 100644
--- a/compiler/image_test.cc
+++ b/compiler/image_test.cc
@@ -288,17 +288,14 @@
 }
 
 TEST_F(ImageTest, WriteReadUncompressed) {
-  TEST_DISABLED_FOR_READ_BARRIER();  // b/27578460
   TestWriteRead(ImageHeader::kStorageModeUncompressed);
 }
 
 TEST_F(ImageTest, WriteReadLZ4) {
-  TEST_DISABLED_FOR_READ_BARRIER();  // b/27578460
   TestWriteRead(ImageHeader::kStorageModeLZ4);
 }
 
 TEST_F(ImageTest, WriteReadLZ4HC) {
-  TEST_DISABLED_FOR_READ_BARRIER();  // b/27578460
   TestWriteRead(ImageHeader::kStorageModeLZ4HC);
 }