Clamp parsed doubles to float representable values

Parts of our rendering assumes incoming doubles can still be sane
floats.

Pick-to: 6.1 6.0 5.15 5.12
Fixes: QTBUG-91507
Change-Id: I7086a121e1b5ed47695a1251ea90e774dd8f148d
Reviewed-by: Robert Löhning <robert.loehning@qt.io>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/svg/qsvghandler.cpp

@@ -680,7 +680,8 @@ static qreal toDouble(const QChar *&str)
             val = -val;
     } else {
         val = QByteArray::fromRawData(temp, pos).toDouble();
-        if (qFpClassify(val) != FP_NORMAL)
+        // Do not tolerate values too wild to be represented normally by floats
+        if (qFpClassify(float(val)) != FP_NORMAL)
             val = 0;
     }
     return val;
@@ -3036,6 +3037,8 @@ static QSvgStyleProperty *createRadialGradientNode(QSvgNode *node,
         ncy = toDouble(cy);
     if (!r.isEmpty())
         nr = toDouble(r);
+    if (nr < 0.5)
+        nr = 0.5;
 
     qreal nfx = ncx;
     if (!fx.isEmpty())