[1.5.4] Upgrade widgets. Add visible to TextOverflow.

Runtime/rendering/paragraph.cs

 
         /// Use an ellipsis to indicate that the text has overflowed.
         ellipsis,
+        
+        /// Render overflowing text outside of its container.
+        visible,
     }
 
 
 
         TextOverflow _overflow;
         readonly TextPainter _textPainter;
-        bool _hasVisualOverflow = false;
+        bool _needsClipping = false;
 
         List<TextBox> _selectionRects;
 
         protected override void performLayout() {
             this._layoutTextWithConstraints(this.constraints);
             var textSize = this._textPainter.size;
-            var didOverflowHeight = this._textPainter.didExceedMaxLines;
+            var textDidExceedMaxLines = this._textPainter.didExceedMaxLines;
+            var didOverflowHeight = this.size.height < textSize.height || textDidExceedMaxLines;
-            this._hasVisualOverflow = didOverflowWidth || didOverflowHeight;
+            var hasVisualOverflow = didOverflowWidth || didOverflowHeight;
+            if (hasVisualOverflow) {
+                switch (this._overflow) {
+                case TextOverflow.visible:
+                    this._needsClipping = false;
+                    break;
+                case TextOverflow.clip:
+                case TextOverflow.ellipsis:
+                case TextOverflow.fade:
+                    this._needsClipping = true;
+                    break;
+                }
+            }
+            else {
+                this._needsClipping = false;
+            }
 
             this._selectionRects = null;
         }
             this._layoutTextWithConstraints(this.constraints);
             var canvas = context.canvas;
 
-            if (this._hasVisualOverflow) {
+            if (this._needsClipping) {
                 var bounds = offset & this.size;
                 canvas.save();
                 canvas.clipRect(bounds);
             }
 
             this._textPainter.paint(canvas, offset);
-            if (this._hasVisualOverflow) {
+            if (this._needsClipping) {
                 canvas.restore();
             }
         }

Runtime/widgets/fade_in_image.cs

         ) {
             D.assert(placeholder != null);
             D.assert(image != null);
-            D.assert(fadeOutDuration != null);
-            D.assert(fadeOutCurve != null);
-            D.assert(fadeInDuration != null);
-            D.assert(fadeInCurve != null);
-            D.assert(alignment != null);
+            fadeOutDuration = fadeOutDuration ?? new TimeSpan(0, 0, 0, 0, 300);
+            fadeOutCurve = fadeOutCurve ?? Curves.easeOut;
+            fadeInDuration = fadeInDuration ?? new TimeSpan(0, 0, 0, 0, 700);
+            fadeInCurve = Curves.easeIn;
+            alignment = alignment ?? Alignment.center;
             var imageProvider = placeholderScale != null
                 ? new ExactAssetImage(placeholder, bundle: bundle, scale: placeholderScale ?? 1.0f)
                 : (ImageProvider) new AssetImage(placeholder, bundle: bundle);

Runtime/widgets/icon.cs

 using Unity.UIWidgets.foundation;
 using Unity.UIWidgets.painting;
+using Unity.UIWidgets.rendering;
 using Unity.UIWidgets.ui;
 using TextStyle = Unity.UIWidgets.painting.TextStyle;
 
             }
 
             Widget iconWidget = new RichText(
+                overflow: TextOverflow.visible,
                 text: new TextSpan(
                     text: new string(new[] {(char) this.icon.codePoint}),
                     style: new TextStyle(

Runtime/widgets/nested_scroll_view.cs

             ScrollPhysics physics = null,
             NestedScrollViewHeaderSliversBuilder headerSliverBuilder = null,
             Widget body = null,
-            DragStartBehavior dragStartBehavior = DragStartBehavior.down
+            DragStartBehavior dragStartBehavior = DragStartBehavior.start
         ) : base(key: key) {
             D.assert(headerSliverBuilder != null);
             D.assert(body != null);
             ScrollController controller,
             List<Widget> slivers,
             SliverOverlapAbsorberHandle handle,
-            DragStartBehavior dragStartBehavior = DragStartBehavior.down
+            DragStartBehavior dragStartBehavior = DragStartBehavior.start
         ) : base(
             scrollDirection: scrollDirection,
             reverse: reverse,

Tests/Editor/Paragraph.cs

             return null;
         }
 
-        RenderBox box(RenderParagraph p, int width = 200, int height = 200) {
+        RenderBox box(RenderParagraph p, int width = 200, int height = 600) {
             return new RenderConstrainedOverflowBox(
                     minWidth: width,
                     maxWidth: width,
                     child: p
-                )
-                ;
+                );
         }
 
         RenderBox flexItemBox(RenderParagraph p, int width = 200, int height = 150) {