Revert "Revert "x86/x86-64: Avoid temporary for read barrier field load.""

Fixed the fault handler recognizing the TEST instruction and
fault address within the lock word. Added tests to 439-npe.

Bug: 29966877
Bug: 12687968
Test: Tested with ART_USE_READ_BARRIER=true on host.
Test: Tested with ART_USE_READ_BARRIER=true ART_HEAP_POISONING=true on host.

This reverts commit ccf15bca330f9a23337b1a4b5850f7fcc6c1bf15.

Change-Id: I8990def5f719c9205bf6e5fdba32027fa82bec50
diff --git a/compiler/utils/x86/assembler_x86.cc b/compiler/utils/x86/assembler_x86.cc
index f1a9915..f2ef41f 100644
--- a/compiler/utils/x86/assembler_x86.cc
+++ b/compiler/utils/x86/assembler_x86.cc
@@ -1148,6 +1148,23 @@
 }
 
 
+void X86Assembler::testb(const Address& dst, const Immediate& imm) {
+  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+  EmitUint8(0xF6);
+  EmitOperand(EAX, dst);
+  CHECK(imm.is_int8());
+  EmitUint8(imm.value() & 0xFF);
+}
+
+
+void X86Assembler::testl(const Address& dst, const Immediate& imm) {
+  AssemblerBuffer::EnsureCapacity ensured(&buffer_);
+  EmitUint8(0xF7);
+  EmitOperand(0, dst);
+  EmitImmediate(imm);
+}
+
+
 void X86Assembler::andl(Register dst, Register src) {
   AssemblerBuffer::EnsureCapacity ensured(&buffer_);
   EmitUint8(0x23);