LayoutBoxModelObject::HasNonEmptyLayoutSize ignores SVG model objects

Extend the DCHECK to also cover SVG layout objects. The IsBox() check
should cover the SVG root, and if it is zero-sized any descendant should
not be considered to have a "non-empty" layout size. Overflow is
disregarded (as it seems to be in general in this method.)

Bug: 769459
Change-Id: Iea15b86032094a15608b614f5baa1057c5d6a686
Reviewed-on: https://chromium-review.googlesource.com/689997Reviewed-by: Philip Rogers <pdr@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#505072}

third_party/WebKit/Source/core/exported/WebElementTest.cpp

@@ -50,6 +50,11 @@ static const char kBlockWithText[] =
     "  <div>Hello</div> "
     "</div>";
 
+static const char kBlockWithEmptyZeroSizedSVG[] =
+    "<div id='testElement'>"
+    "  <svg height='0'><g><rect width='100' height='100'/></g></svg> "
+    "</div>";
+
 static const char kBlockWithInlines[] =
     "<div id='testElement'>"
     "  <span>Hello</span> "
@@ -99,6 +104,9 @@ TEST_F(WebElementTest, HasNonEmptyLayoutSize) {
   InsertHTML(kBlockWithEmptyInlines);
   EXPECT_FALSE(TestElement().HasNonEmptyLayoutSize());
 
+  InsertHTML(kBlockWithEmptyZeroSizedSVG);
+  EXPECT_FALSE(TestElement().HasNonEmptyLayoutSize());
+
   InsertHTML(kBlockWithContinuations);
   EXPECT_TRUE(TestElement().HasNonEmptyLayoutSize());
 

third_party/WebKit/Source/core/layout/LayoutBoxModelObject.cpp

@@ -603,7 +603,7 @@ bool LayoutBoxModelObject::HasNonEmptyLayoutSize() const {
         if (!layout_inline.LinesBoundingBox().IsEmpty())
           return true;
       } else {
-        DCHECK(object->IsText());
+        DCHECK(object->IsText() || object->IsSVG());
       }
     }
   }