[x64] Make r12 allocatable.

src/x64/assembler-x64.cc

Index: src/x64/assembler-x64.cc
diff --git a/src/x64/assembler-x64.cc b/src/x64/assembler-x64.cc
index dcfa01fd0e3d3883606248663760633c6402b0fb..118018fd1960dfcdbcb4673d8da0cd03e0e0364a 100644
--- a/src/x64/assembler-x64.cc
+++ b/src/x64/assembler-x64.cc
@@ -156,12 +156,12 @@ void RelocInfo::PatchCode(byte* instructions, int instruction_count) {
 
 const int
     Register::kRegisterCodeByAllocationIndex[kMaxNumAllocatableRegisters] = {
-  // rax, rbx, rdx, rcx, rsi, rdi, r8, r9, r11, r14, r15
-  0, 3, 2, 1, 6, 7, 8, 9, 11, 14, 15
+  // rax, rbx, rdx, rcx, rsi, rdi, r8, r9, r11, r12, r14, r15
+  0, 3, 2, 1, 6, 7, 8, 9, 11, 12, 14, 15
 };
 
 const int Register::kAllocationIndexByRegisterCode[kNumRegisters] = {
-  0, 3, 2, 1, -1, -1, 4, 5, 6, 7, -1, 8, -1, -1, 9, 10
+  0, 3, 2, 1, -1, -1, 4, 5, 6, 7, -1, 8, 9, -1, 10, 11
 };