Fixed crashes exposed though fuzzing.

src/arm/macro-assembler-arm.h

Index: src/arm/macro-assembler-arm.h
diff --git a/src/arm/macro-assembler-arm.h b/src/arm/macro-assembler-arm.h
index 97b2575fc3595007ab8f2708d30b3b71f3398679..4897064fc68f88e01510b4bf48962995dc0ff4f6 100644
--- a/src/arm/macro-assembler-arm.h
+++ b/src/arm/macro-assembler-arm.h
@@ -661,6 +661,12 @@ class MacroAssembler: public Assembler {
   // handler chain.
   void ThrowUncatchable(Register value);
 
+  // Throw a message string as an exception.
+  void Throw(BailoutReason reason);
+
+  // Throw a message string as an exception if a condition is not true.
+  void ThrowIf(Condition cc, BailoutReason reason);
+
   // ---------------------------------------------------------------------------
   // Inline caching support
 
@@ -1341,6 +1347,11 @@ class MacroAssembler: public Assembler {
 
   void JumpIfNotUniqueName(Register reg, Label* not_unique_name);
 
+  void EmitSeqStringSetCharCheck(Register string,
+                                 Register index,
+                                 Register value,
+                                 uint32_t encoding_mask);
+
   // ---------------------------------------------------------------------------
   // Patching helpers.