Remove redundant isInline function

The same isInline function is defined in EditingUtilities.cpp and
IndentOutdentCommand.cpp. This CL adds isInline declaration in
EditingUtilities.h so that it can remove the same function from
IndentOutdentCommand.cpp.

In addition, it uses Node::computedStyle() rather than layout object
to reduce dependency of layout tree.

BUG=none

Review-Url: https://codereview.chromium.org/2105653004
Cr-Commit-Position: refs/heads/master@{#402689}

third_party/WebKit/Source/core/editing/EditingUtilities.cpp

@@ -29,6 +29,7 @@
 #include "core/HTMLNames.h"
 #include "core/dom/Document.h"
 #include "core/dom/ElementTraversal.h"
+#include "core/dom/NodeComputedStyle.h"
 #include "core/dom/Range.h"
 #include "core/dom/Text.h"
 #include "core/dom/shadow/ShadowRoot.h"
@@ -764,7 +765,7 @@ bool isEnclosingBlock(const Node* node)
 
 bool isInline(const Node* node)
 {
-    return node && node->layoutObject() && node->layoutObject()->isInline();
+    return node && node->computedStyle()->display() == INLINE;
 }
 
 // TODO(yosin) Deploy this in all of the places where |enclosingBlockFlow()| and

third_party/WebKit/Source/core/editing/EditingUtilities.h

@@ -150,6 +150,7 @@ bool isTabHTMLSpanElement(const Node*);
 bool isTabHTMLSpanElementTextNode(const Node*);
 bool isMailHTMLBlockquoteElement(const Node*);
 bool isDisplayInsideTable(const Node*);
+bool isInline(const Node*);
 bool isTableCell(const Node*);
 bool isEmptyTableCell(const Node*);
 bool isTableStructureNode(const Node*);

third_party/WebKit/Source/core/editing/commands/IndentOutdentCommand.cpp

@@ -54,12 +54,6 @@ static bool isHTMLListOrBlockquoteElement(const Node* node)
     return isHTMLUListElement(element) || isHTMLOListElement(element) || element.hasTagName(blockquoteTag);
 }
 
-static bool isInline(const Node* node)
-{
-    return node && node->layoutObject() && node->layoutObject()->isInline();
-}
-
-
 IndentOutdentCommand::IndentOutdentCommand(Document& document, EIndentType typeOfAction)
     : ApplyBlockElementCommand(document, blockquoteTag, "margin: 0 0 0 40px; border: none; padding: 0px;")
     , m_typeOfAction(typeOfAction)