Bug 1278868 - add MOZ_FALLTHROUGH in arm jit code; r=jandem

This macro is a little clearer than comments and also avoids warnings
when compiling with clang.

js/src/jit/arm/MacroAssembler-arm.cpp

@@ -6,6 +6,7 @@
 
 #include "jit/arm/MacroAssembler-arm.h"
 
+#include "mozilla/Attributes.h"
 #include "mozilla/Casting.h"
 #include "mozilla/DebugOnly.h"
 #include "mozilla/MathAlgorithms.h"
@@ -4906,14 +4907,14 @@ MacroAssembler::callWithABIPost(uint32_t stackAdjust, MoveOp::Type result)
         if (!UseHardFpABI()) {
             // Move double from r0/r1 to ReturnFloatReg.
             ma_vxfer(r0, r1, ReturnDoubleReg);
-            break;
         }
+        break;
       case MoveOp::FLOAT32:
         if (!UseHardFpABI()) {
             // Move float32 from r0 to ReturnFloatReg.
             ma_vxfer(r0, ReturnFloat32Reg.singleOverlay());
-            break;
         }
+        break;
       case MoveOp::GENERAL:
         break;
 

js/src/jit/arm/disasm/Disasm-arm.cpp

@@ -1903,7 +1903,7 @@ Decoder::DecodeSpecialCondition(Instruction* instr)
             }
             break;
         }
-        // else fall through
+        MOZ_FALLTHROUGH;
       case 0xB:
         if ((instr->Bits(22, 20) == 5) && (instr->Bits(15, 12) == 0xf)) {
             int Rn = instr->Bits(19, 16);