Revert^4 "Compiler changes for bitstring based type checks."

Disabled the build time flag. (No image version bump needed.)

Bug: 26687569
Bug: 64692057
Bug: 76420366

This reverts commit 3fbd3ad99fad077e5c760e7238bcd55b07d4c06e.

Change-Id: I5d83c4ce8a7331c435d5155ac6e0ce1c77d60004
diff --git a/runtime/arch/x86/quick_entrypoints_x86.S b/runtime/arch/x86/quick_entrypoints_x86.S
index 5c4ae4e..df43aef 100644
--- a/runtime/arch/x86/quick_entrypoints_x86.S
+++ b/runtime/arch/x86/quick_entrypoints_x86.S
@@ -1432,6 +1432,10 @@
 END_FUNCTION art_quick_instance_of
 
 DEFINE_FUNCTION art_quick_check_instance_of
+    // Type check using the bit string passes null as the target class. In that case just throw.
+    testl %ecx, %ecx
+    jz .Lthrow_class_cast_exception_for_bitstring_check
+
     PUSH eax                              // alignment padding
     PUSH ecx                              // pass arg2 - checked class
     PUSH eax                              // pass arg1 - obj
@@ -1449,6 +1453,7 @@
     addl LITERAL(4), %esp
     CFI_ADJUST_CFA_OFFSET(-4)
 
+.Lthrow_class_cast_exception_for_bitstring_check:
     SETUP_SAVE_ALL_CALLEE_SAVES_FRAME ebx, ebx // save all registers as basis for long jump context
     // Outgoing argument set up
     PUSH eax                              // alignment padding