Update DeviceMotionEvent IDL to match the specification.

third_party/WebKit/Source/modules/device_orientation/DeviceMotionData.cpp

 /*
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *  * Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *  * Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 104 matching lines @@
       init.hasAcceleration()
           ? DeviceMotionData::Acceleration::create(init.acceleration())
           : nullptr,
       init.hasAccelerationIncludingGravity()
           ? DeviceMotionData::Acceleration::create(
                 init.accelerationIncludingGravity())
           : nullptr,
       init.hasRotationRate()
           ? DeviceMotionData::RotationRate::create(init.rotationRate())
           : nullptr,
-      init.hasInterval() ? init.interval() : 0);
+      init.interval());
 }
 
 DeviceMotionData* DeviceMotionData::create(const device::MotionData& data) {
   return DeviceMotionData::create(
       DeviceMotionData::Acceleration::create(
           data.has_acceleration_x, data.acceleration_x, data.has_acceleration_y,
           data.acceleration_y, data.has_acceleration_z, data.acceleration_z),
       DeviceMotionData::Acceleration::create(
           data.has_acceleration_including_gravity_x,
           data.acceleration_including_gravity_x,
@@ skipping 37 matching lines @@
        m_accelerationIncludingGravity->canProvideZ());
   const bool hasRotationRate =
       m_rotationRate &&
       (m_rotationRate->canProvideAlpha() || m_rotationRate->canProvideBeta() ||
        m_rotationRate->canProvideGamma());
 
   return hasAcceleration || hasAccelerationIncludingGravity || hasRotationRate;
 }
 
 }  // namespace blink