Avoid infinite loop when gathering "g" element styles

Same way of how fdo#74743 is fixed 3b7472b2

Change-Id: If6cc8eb6ff89b0081f27ff75a9b60a3e81cff1bd
Reviewed-on: https://gerrit.libreoffice.org/10326Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
Tested-by: Tomaž Vajngerl <quikee@gmail.com>

svgio/qa/cppunit/SvgImportTest.cxx

@@ -82,6 +82,9 @@ void Test::testStyles()
     Primitive2DSequence maSequenceRectWithParentStyle = parseSvg("/svgio/qa/cppunit/data/RectWithParentStyles.svg");
     CPPUNIT_ASSERT_EQUAL(1, (int) maSequenceRectWithParentStyle.getLength());
 
+    Primitive2DSequence maSequenceRectWithStylesByGroup = parseSvg("/svgio/qa/cppunit/data/RectWithStylesByGroup.svg");
+    CPPUNIT_ASSERT_EQUAL(1, (int) maSequenceRectWithStylesByGroup.getLength());
+
     // TODO: Test if the 3 sequences are equal..
     //const Primitive2DReference xReference(maSequenceRect[0]);
 }

svgio/source/svgreader/svggnode.cxx

@@ -43,7 +43,13 @@ namespace svgio
 
         const SvgStyleAttributes* SvgGNode::getSvgStyleAttributes() const
         {
-            return checkForCssStyle(OUString("g"), maSvgStyleAttributes);
+            const SvgStyleAttributes* aCheckCssStyle = checkForCssStyle(OUString("g"), maSvgStyleAttributes);
+            const SvgStyleAttributes* aGetCssStyleParent = maSvgStyleAttributes.getCssStyleParent();
+
+            if (aGetCssStyleParent == NULL)
+                return aCheckCssStyle;
+
+            return aGetCssStyleParent;
         }
 
         void SvgGNode::parseAttribute(const OUString& rTokenName, SVGToken aSVGToken, const OUString& aContent)