Compute margin block start for 1st block in LayoutNG root constraint space

third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm_test.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/ng/ng_block_layout_algorithm.h"
 
 #include "core/layout/ng/ng_box.h"
 #include "core/layout/ng/ng_constraint_space.h"
 #include "core/layout/ng/ng_physical_fragment.h"
 #include "core/layout/ng/ng_length_utils.h"
 #include "core/layout/ng/ng_units.h"
 #include "core/style/ComputedStyle.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace blink {
 namespace {
 
 class NGBlockLayoutAlgorithmTest : public ::testing::Test {
  protected:
   void SetUp() override { style_ = ComputedStyle::create(); }
 
-  NGPhysicalFragment* RunBlockLayoutAlgorithm(const NGConstraintSpace* space,
+  NGPhysicalFragment* RunBlockLayoutAlgorithm(NGConstraintSpace* space,
                                               NGBox* first_child) {
     NGBlockLayoutAlgorithm algorithm(style_, first_child);
     NGPhysicalFragment* frag;
+    space->SetIsRoot();
     while (!algorithm.Layout(space, &frag))
       continue;
     return frag;
   }
 
   RefPtr<ComputedStyle> style_;
 };
 
 TEST_F(NGBlockLayoutAlgorithmTest, FixedSize) {
   style_->setWidth(Length(30, Fixed));
@@ skipping 445 matching lines @@
 
   EXPECT_EQ(frag->Width(), LayoutUnit(kWidth + kPaddingLeft));
   EXPECT_EQ(frag->Type(), NGPhysicalFragmentBase::FragmentBox);
   ASSERT_EQ(frag->Children().size(), 1UL);
 
   const NGPhysicalFragmentBase* child = frag->Children()[0];
   EXPECT_EQ(child->Width(), LayoutUnit(12));
 }
 }  // namespace
 }  // namespace blink