CSS Typed OM: Implement TransformValue::asMatrix

CSS Typed OM: Implement TransformValue::asMatrix

TransformValue::asMatrix returns:
 - the identity matrix (2d) when the components are empty
 - the multiplication of all the transform components in order

Please note:
 - this is a very naive implementation

Alternative improved approaches to consider:

1. Use switch statement and type casts.
  Have MatrixTransformComponent::multiplySelf
  take arguments TransformComponent and ExceptionState

  Then have a switch statement for each type and use
  the underlying TransformationMatrix operations, rather than
  unnecessarily making O(n) MatrixTransformComponents.
  It is also more optimised for operations such as scale etc
  where it only multiplies the necessary values, rather
  than the entire matrix.

2. Expose TransformValue to TransformationMatrix.
  Implement similar to 1. in TransformValue.
  Has the pro that MatrixTransformComponent could be kept
  as immutable.

BUG=545318

[meade_UTC10, 2017-02-27 07:37:59]

Description was changed from

==========
CSS Typed OM: Implement TransformValue::asMatrix

TransformValue::asMatrix returns:
 - the identity matrix (2d) when the components are empty
 - the multiplication of all the transform components in order

Please note:
 - this is a very naive implementation

Alternative improved approaches to consider:

1. Use switch statement and type casts.
  Have MatrixTransformComponent::multiplySelf
  take arguments TransformComponent and ExceptionState

  Then have a switch statement for each type and use
  the underlying TransformationMatrix operations, rather than
  unnecessarily making O(n) MatrixTransformComponents.
  It is also more optimised for operations such as scale etc
  where it only multiplies the necessary values, rather
  than the entire matrix.

2. Expose TransformValue to TransformationMatrix.
  Implement similar to 1. in TransformValue.
  Has the pro that MatrixTransformComponent could be kept
  as immutable.

BUG=545318
==========

to

==========
CSS Typed OM: Implement TransformValue::asMatrix

TransformValue::asMatrix returns:
 - the identity matrix (2d) when the components are empty
 - the multiplication of all the transform components in order

Please note:
 - this is a very naive implementation

Alternative improved approaches to consider:

1. Use switch statement and type casts.
  Have MatrixTransformComponent::multiplySelf
  take arguments TransformComponent and ExceptionState

  Then have a switch statement for each type and use
  the underlying TransformationMatrix operations, rather than
  unnecessarily making O(n) MatrixTransformComponents.
  It is also more optimised for operations such as scale etc
  where it only multiplies the necessary values, rather
  than the entire matrix.

2. Expose TransformValue to TransformationMatrix.
  Implement similar to 1. in TransformValue.
  Has the pro that MatrixTransformComponent could be kept
  as immutable.

BUG=545318
==========