Revert of DevTools: CSSStyleDeclaration::getPropertyShorthand should …

…return empty string for shorthands. (patchset #1 id:1 of https://codereview.chromium.org/1677093003/ )

Reason for revert:
This breaks beta build: crbug.com/585266

Original issue's description:
> DevTools: CSSStyleDeclaration::getPropertyShorthand should return empty string for shorthands.
>
> The getPropertyShorthand method should return empty string if called
> with a shorthand name.
>
> This used to work because shorthand got expanded into longhands internally
> in the CSSStyleDeclaration, which is not the case anymore with the
> custom CSS properties.
>
> BUG=583300
> R=pfeldman, sergeyv
>
> Review URL: https://codereview.chromium.org/1662743003
>
> Cr-Commit-Position: refs/heads/master@{#373749}
> (cherry picked from commit ad56cde)
>
> Committed: https://chromium.googlesource.com/chromium/src/+/129f4162a8c5adf0a0f5ce174e3109ca6c714a92

[email protected],[email protected]
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=583300

Review URL: https://codereview.chromium.org/1684453002

Cr-Commit-Position: refs/branch-heads/2623@{#310}
Cr-Branched-From: 92d7753-refs/heads/master@{#369907}

third_party/WebKit/Source/core/core.gypi

@@ -3859,7 +3859,6 @@
             'css/CSSCalculationValueTest.cpp',
             'css/CSSFontFaceTest.cpp',
             'css/CSSSelectorTest.cpp',
-            'css/CSSStyleDeclarationTest.cpp',
             'css/CSSStyleSheetResourceTest.cpp',
             'css/CSSTestHelper.cpp',
             'css/CSSTestHelper.h',

third_party/WebKit/Source/core/css/CSSStyleRule.h

@@ -31,7 +31,7 @@ class CSSStyleDeclaration;
 class StyleRuleCSSStyleDeclaration;
 class StyleRule;
 
-class CORE_EXPORT CSSStyleRule final : public CSSRule {
+class CSSStyleRule final : public CSSRule {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static PassRefPtrWillBeRawPtr<CSSStyleRule> create(StyleRule* rule, CSSStyleSheet* sheet)

third_party/WebKit/Source/core/css/PropertySetCSSStyleDeclaration.cpp

@@ -23,7 +23,6 @@
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "core/HTMLNames.h"
-#include "core/StylePropertyShorthand.h"
 #include "core/css/CSSCustomPropertyDeclaration.h"
 #include "core/css/CSSKeyframesRule.h"
 #include "core/css/CSSStyleSheet.h"
@@ -207,8 +206,6 @@ String AbstractPropertySetCSSStyleDeclaration::getPropertyShorthand(const String
     // Custom properties don't have shorthands, so we can ignore them here.
     if (!propertyID)
         return String();
-    if (isShorthandProperty(propertyID))
-        return String();
     CSSPropertyID shorthandID = propertySet().getPropertyShorthand(propertyID);
     if (!shorthandID)
         return String();