Use round() [not roundf()] in RoundedIntPoint(const DoublePoint&)

This avoids the implicit conversion to float, which can lead to loss of
precision.

Bug: 836722
Change-Id: I66ea0f42823347b17e41e5d823aaf766429eacbf
Reviewed-on: https://chromium-review.googlesource.com/1027710Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#553543}

third_party/blink/renderer/platform/BUILD.gn

@@ -1797,6 +1797,7 @@ jumbo_source_set("blink_platform_unittests_sources") {
     "fonts/symbols_iterator_test.cc",
     "fonts/typesetting_features_test.cc",
     "fonts/unicode_range_set_test.cc",
+    "geometry/double_point_test.cc",
     "geometry/double_rect_test.cc",
     "geometry/float_box_test.cc",
     "geometry/float_box_test_helpers.cc",

third_party/blink/renderer/platform/geometry/double_point.h

@@ -111,7 +111,7 @@ inline DoublePoint operator-(const DoublePoint& a, const DoubleSize& b) {
 }
 
 inline IntPoint RoundedIntPoint(const DoublePoint& p) {
-  return IntPoint(clampTo<int>(roundf(p.X())), clampTo<int>(roundf(p.Y())));
+  return IntPoint(clampTo<int>(round(p.X())), clampTo<int>(round(p.Y())));
 }
 
 inline IntPoint CeiledIntPoint(const DoublePoint& p) {

third_party/blink/renderer/platform/geometry/double_point_test.cc

+// Copyright 2018 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 "third_party/blink/renderer/platform/geometry/double_point.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace blink {
+
+TEST(DoublePointTest, RoundedIntPoint) {
+  // Value not exactly representable as a float.
+  DoublePoint p1(16777217.0, -16777217.0);
+  IntPoint rounded_p1 = RoundedIntPoint(p1);
+  EXPECT_EQ(16777217, rounded_p1.X());
+  EXPECT_EQ(-16777217, rounded_p1.Y());
+}
+
+}  // namespace blink