Bug 1278303 part 1 - Prevent uses of TempObject new operator on MIR Instructions. r=jandem

        // the block itself.

        MOZ_ASSERT(def->isConstant());

        MConstant* constant = new(alloc) MConstant(*def->toConstant());

        MConstant* constant = MConstant::Copy(alloc, def->toConstant());

        oldPreheader->insertBefore(*oldPreheader->begin(), constant);

        return constant;

    }

{

    MResumePoint* resumePoint_;

  protected:

    // All MInstructions are using the "MFoo::New(alloc)" notation instead of

    // the TempObject new operator. This code redefines the new operator as

    // protected, and delegates to the TempObject new operator. Thus, the

    // following code prevents calls to "new(alloc) MFoo" outside the MFoo

    // members.

    template <typename... Args>

    inline void* operator new(size_t nbytes, Args&&... args) {

        return TempObject::operator new(nbytes, mozilla::Forward<Args>(args)...);

    }

  public:

    MInstruction()

      : resumePoint_(nullptr)

    static MConstant* NewInt64(TempAllocator& alloc, int64_t i);

    static MConstant* NewAsmJS(TempAllocator& alloc, const Value& v, MIRType type);

    static MConstant* NewConstraintlessObject(TempAllocator& alloc, JSObject* v);

    static MConstant* Copy(TempAllocator& alloc, MConstant* src) {

        return new(alloc) MConstant(*src);

    }

    // Try to convert this constant to boolean, similar to js::ToBoolean.

    // Returns false if the type is MIRType::Magic*.