Add assertions to limit register count for VSTM and VLDM.

src/arm/assembler-arm.cc

Index: src/arm/assembler-arm.cc
diff --git a/src/arm/assembler-arm.cc b/src/arm/assembler-arm.cc
index d875796217ddf3aa2f21c72e26bfa8bdfb320400..ba4c81617b5df96b76969e9f7b47a98108eb32f7 100644
--- a/src/arm/assembler-arm.cc
+++ b/src/arm/assembler-arm.cc
@@ -1855,6 +1855,7 @@ void  Assembler::vstm(BlockAddrMode am,
   int sd, d;
   first.split_code(&sd, &d);
   int count = last.code() - first.code() + 1;
+  ASSERT(count <= 16);
   emit(cond | B27 | B26 | am | d*B22 | base.code()*B16 | sd*B12 |
        0xB*B8 | count*2);
 }
@@ -1875,6 +1876,7 @@ void  Assembler::vldm(BlockAddrMode am,
   int sd, d;
   first.split_code(&sd, &d);
   int count = last.code() - first.code() + 1;
+  ASSERT(count <= 16);
   emit(cond | B27 | B26 | am | d*B22 | B20 | base.code()*B16 | sd*B12 |
        0xA*B8 | count);
 }