message: Speed up ExpectTensorEqual and Near in non-opt mode by using access to the raw
  buffer instead of through eigen accessor.
diff: @@ -166,10 +166,11 @@ struct Expector<T, false> {
  static void Equal(const Tensor& x, const Tensor& y) {
  ASSERT_EQ(x.dtype(), DataTypeToEnum<T>::v());
  AssertSameTypeDims(x, y);
  - auto a = x.flat<T>();
  - auto b = y.flat<T>();
  - for (int i = 0; i < a.size(); ++i) {
  - ExpectEqual(a(i), b(i));
  + const auto size = x.NumElements();
  + const T* a = x.flat<T>().data();
  + const T* b = y.flat<T>().data();
  + for (int i = 0; i < size; ++i) {
  + ExpectEqual(a[i], b[i]);
  }
  }
  };
  @@ -182,10 +183,11 @@ struct Expector<T, true> {
  static void Equal(const Tensor& x, const Tensor& y) {
  ASSERT_EQ(x.dtype(), DataTypeToEnum<T>::v());
  AssertSameTypeDims(x, y);
  - auto a = x.flat<T>();
  - auto b = y.flat<T>();
  - for (int i = 0; i < a.size(); ++i) {
  - ExpectEqual(a(i), b(i));
  + const auto size = x.NumElements();
  + const T* a = x.flat<T>().data();
  + const T* b = y.flat<T>().data();
  + for (int i = 0; i < size; ++i) {
  + ExpectEqual(a[i], b[i]);
  }
  }
  @@ -199,10 +201,11 @@ struct Expector<T, true> {
  static void Near(const Tensor& x, const Tensor& y, const double abs_err) {
  ASSERT_EQ(x.dtype(), DataTypeToEnum<T>::v());
  AssertSameTypeDims(x, y);
  - auto a = x.flat<T>();
  - auto b = y.flat<T>();
  - for (int i = 0; i < a.size(); ++i) {
  - Near(a(i), b(i), abs_err, i);
  + const auto size = x.NumElements();
  + const T* a = x.flat<T>().data();
  + const T* b = y.flat<T>().data();
  + for (int i = 0; i < size; ++i) {
  + Near(a[i], b[i], abs_err, i);
  }
  }
  };
  