The missing value default for <area shape> is 'rect'

There is no invalid value default, so the missing value default will
apply in that case too.
The 'Unknown' HTMLAreaElement::Shape enumeration value is no longer
needed, so remove it.

Also add support for the non-conforming <area shape> values:

 * 'circ'     (alias for 'circle')
 * 'polygon'  (alias for 'poly')
 * 'rectangle (alias for 'rect')

Because 'rect' (and hence 'rectangle') is the same as the missing
value default we don't need any explicit checks for these values.

https://html.spec.whatwg.org/multipage/embedded-content.html#attr-area-shape

BUG=578125

Review URL: https://codereview.chromium.org/1632133007

Cr-Commit-Position: refs/heads/master@{#371731}

third_party/WebKit/LayoutTests/fast/html/area-shape-expected.txt

-
-This is a testharness.js-based test.
-PASS missing value default: "2,2,10,10" (null) 
-FAIL missing value default: "20,40,10" (null) assert_equals: elementFromPoint(21, 41) expected Element node <img src="resources/images/blue-border.png" usemap="#x" i... but got Element node <area id="area" shape="null" coords="20,40,10"></area>
-PASS missing value default: null (null) 
-PASS invalid value default: "2,2,10,10" (foobar invalid) 
-PASS invalid value default: "2,2,10,10" () 
-PASS empty string: "" (default) 
-PASS omitted coords: null (DEFAULT) 
-PASS simple: "20,40,10" (circle) 
-PASS simple: "20,40,10" (circ) 
-PASS simple: "20,40,10" (CIRCLE) 
-PASS simple: "20,40,10" (CIRC) 
-FAIL LATIN CAPITAL LETTER I WITH DOT ABOVE: "20,40,10" (CİRCLE) assert_equals: elementFromPoint(21, 41) expected Element node <img src="resources/images/blue-border.png" usemap="#x" i... but got Element node <area id="area" shape="CİRCLE" coords="20,40,10"></area>
-FAIL LATIN SMALL LETTER DOTLESS I: "20,40,10" (cırcle) assert_equals: elementFromPoint(21, 41) expected Element node <img src="resources/images/blue-border.png" usemap="#x" i... but got Element node <area id="area" shape="cırcle" coords="20,40,10"></area>
-PASS simple: "100,100,120,100,100,120" (poly) 
-PASS simple: "100,100,120,100,100,120" (polygon) 
-Harness: the test ran to completion.
-

third_party/WebKit/Source/core/html/HTMLAreaElement.cpp

@@ -49,7 +49,7 @@ using namespace HTMLNames;
 inline HTMLAreaElement::HTMLAreaElement(Document& document)
     : HTMLAnchorElement(areaTag, document)
     , m_lastSize(-1, -1)
-    , m_shape(Unknown)
+    , m_shape(Rect)
 {
 }
 
@@ -67,14 +67,17 @@ DEFINE_NODE_FACTORY(HTMLAreaElement)
 void HTMLAreaElement::parseAttribute(const QualifiedName& name, const AtomicString& oldValue, const AtomicString& value)
 {
     if (name == shapeAttr) {
-        if (equalIgnoringASCIICase(value, "default"))
+        if (equalIgnoringASCIICase(value, "default")) {
             m_shape = Default;
-        else if (equalIgnoringASCIICase(value, "circle"))
+        } else if (equalIgnoringASCIICase(value, "circle") || equalIgnoringASCIICase(value, "circ")) {
             m_shape = Circle;
-        else if (equalIgnoringASCIICase(value, "poly"))
+        } else if (equalIgnoringASCIICase(value, "polygon") || equalIgnoringASCIICase(value, "poly")) {
             m_shape = Poly;
-        else if (equalIgnoringASCIICase(value, "rect"))
+        } else {
+            // The missing (and implicitly invalid) value default for the
+            // 'shape' attribute is 'rect'.
             m_shape = Rect;
+        }
         invalidateCachedRegion();
     } else if (name == coordsAttr) {
         m_coords = parseHTMLAreaElementCoords(value.string());
@@ -136,19 +139,8 @@ Path HTMLAreaElement::getRegion(const LayoutSize& size) const
     if (m_coords.isEmpty() && m_shape != Default)
         return Path();
 
-    // If element omits the shape attribute, select shape based on number of coordinates.
-    Shape shape = m_shape;
-    if (shape == Unknown) {
-        if (m_coords.size() == 3)
-            shape = Circle;
-        else if (m_coords.size() == 4)
-            shape = Rect;
-        else if (m_coords.size() >= 6)
-            shape = Poly;
-    }
-
     Path path;
-    switch (shape) {
+    switch (m_shape) {
     case Poly:
         if (m_coords.size() >= 6) {
             int numPoints = m_coords.size() / 2;
@@ -177,8 +169,6 @@ Path HTMLAreaElement::getRegion(const LayoutSize& size) const
     case Default:
         path.addRect(FloatRect(FloatPoint(0, 0), FloatSize(size)));
         break;
-    case Unknown:
-        break;
     }
 
     return path;

third_party/WebKit/Source/core/html/HTMLAreaElement.h

@@ -59,7 +59,7 @@ private:
     void updateFocusAppearance(SelectionBehaviorOnFocus) override;
     void setFocus(bool) override;
 
-    enum Shape { Default, Poly, Rect, Circle, Unknown };
+    enum Shape { Default, Poly, Rect, Circle };
     Path getRegion(const LayoutSize&) const;
     void invalidateCachedRegion();