[CI] Refactor replaced element nested intrinsic sizing info extraction

This moves the access to a nested layout contexts (either a frame
embedded via LayoutEmbeddedObject or an SVG image via LayoutImage)
LayoutReplaced (LayoutSVGRoot) from LayoutReplaced to the relevant
subclasses (LayoutEmbeddedObject or LayoutImage.) The goal with this is
to eliminate the use of EmbeddedReplacedContent in LayoutReplaced.

Rather than accessing EmbeddedReplacedContent() and calling
ComputeIntrinsicSizingInfo() on the returned LayoutReplaced, a new
method GetNestedIntrinsicSizingInfo is added instead, and implemented in
the relevant subclasses. In LayoutImage the EmbeddedReplacedContent()
method is kept around (for now), but in LayoutEmbeddedObject it's
removed, and instead rerouted via LocalFrameView.

NeedsPreferredWidthsRecalculation is moved from LayoutEmbeddedContent to
its subclass LayoutEmbeddedObject since this is the only subclass that
can modify its behavior - i.e can represent content that may can affect
the size of its embedder.

The IntrinsicSizingInfo struct is moved out from being an inner class of
LayoutReplaced.

Bug: 798974
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_layout_ng;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Ia617a40d631e6b2e6bb2c9f39a1799766d7f58d6
Reviewed-on: https://chromium-review.googlesource.com/860140
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#528524}
12 files changed