Fix legend to show dash line. (#4892)

Author: polina-c

packages/devtools_app/lib/src/screens/memory/memory_tabs.dart

@@ -43,7 +43,6 @@ class MemoryTabView extends StatelessWidget {
           tabs.add(record.tab);
           tabViews.add(record.tabView);
         }
-        print('rebuilding analytics tabbed view');
         return AnalyticsTabbedView(
           tabs: tabs,
           tabViews: tabViews,

packages/devtools_app/lib/src/screens/memory/primitives/painting.dart

@@ -4,30 +4,23 @@
 
 import 'package:flutter/material.dart';
 
-const _totalDashWidth = 15.0;
+// TODO(polina-c): use the same constants as for dash in the chart.
 const _dashHeight = 2.0;
-const _dashWidth = 4.0;
+const _dashWidth = 5.0;
 const _spaceBetweenDash = 3.0;
 
 Widget createDashWidget(Color color) {
-  return Container(
-    padding: const EdgeInsets.only(right: 20),
-    child: CustomPaint(
-      painter: DashedLine(
-        _totalDashWidth,
-        color,
-        _dashHeight,
-        _dashWidth,
-        _spaceBetweenDash,
-      ),
-      foregroundPainter: DashedLine(
-        _totalDashWidth,
-        color,
-        _dashHeight,
-        _dashWidth,
-        _spaceBetweenDash,
-      ),
-    ),
+  final dash = Container(
+    width: _dashWidth,
+    height: _dashHeight,
+    color: color,
+  );
+  const space = SizedBox(
+    width: _spaceBetweenDash,
+    height: _dashHeight,
+  );
+  return Row(
+    children: [dash, space, dash, space, dash],
   );
 }