Clean up emitInst() in the integrated ARM assembler.

src/IceAssemblerARM32.h

Index: src/IceAssemblerARM32.h
diff --git a/src/IceAssemblerARM32.h b/src/IceAssemblerARM32.h
index 2710e581a0decbb00c05df1cd58b899a0a5c1c10..bec451011cf1723bed5551fcd46e427f7cc34e11 100644
--- a/src/IceAssemblerARM32.h
+++ b/src/IceAssemblerARM32.h
@@ -458,7 +458,10 @@ private:
 
   void bindCfgNodeLabel(const CfgNode *Node) override;
 
-  void emitInst(IValueT Value) { Buffer.emit<IValueT>(Value); }
+  void emitInst(IValueT Value) {
+    AssemblerBuffer::EnsureCapacity _(&Buffer);
+    Buffer.emit<IValueT>(Value);
+  }
 
   // List of possible checks to apply when calling emitType01() (below).
   enum EmitChecks { NoChecks, RdIsPcAndSetFlags };