Fix lint warnings

@@ -133,9 +133,9 @@ class PdfAnnot extends PdfObject {
       } else {
         final List<PdfStream> dests = <PdfStream>[];
         dests.add(dest.ref());
-        if (destRect == null)
+        if (destRect == null) {
           dests.add(PdfStream.string('/Fit'));
-        else {
+        } else {
           dests.add(PdfStream.string('/FitR '));
           dests.add(PdfStream()
             ..putNumList(<double>[

@@ -108,8 +108,9 @@ class PdfOutput {
       os.putString('/Root ');
       os.putStream(rootID.ref());
       os.putString('\n');
-    } else
+    } else {
       throw Exception('Root object is not present in document');
+    }
 
     // the /Info reference (OPTIONAL)
     if (infoID != null) {

@@ -410,9 +410,10 @@ class AspectRatio extends SingleChildWidget {
   void layout(Context context, BoxConstraints constraints,
       {bool parentUsesSize = false}) {
     box = PdfRect.fromPoints(PdfPoint.zero, _applyAspectRatio(constraints));
-    if (child != null)
+    if (child != null) {
       child.layout(context,
           BoxConstraints.tightFor(width: box.width, height: box.height));
+    }
     assert(child.box != null);
   }
 

@@ -77,9 +77,10 @@ class BoxBorder {
           context.canvas.lineTo(box.x, box.top);
         } else if (right && top) {
           context.canvas.closePath();
-        } else
+        } else {
           context.canvas.lineTo(box.x, box.top);
         }
+      }
 
       context.canvas.strokePath();
     }
@@ -151,12 +152,12 @@ class BoxDecoration {
     if (color != null) {
       switch (shape) {
         case BoxShape.rectangle:
-          if (borderRadius == null)
+          if (borderRadius == null) {
             context.canvas.drawRect(box.x, box.y, box.width, box.height);
-          else
+          } else {
             context.canvas.drawRRect(box.x, box.y, box.width, box.height,
                 borderRadius, borderRadius);
-
+          }
           break;
         case BoxShape.circle:
           context.canvas.drawEllipse(box.x + box.width / 2.0,
@@ -259,15 +260,17 @@ class Container extends StatelessWidget {
           child: ConstrainedBox(constraints: const BoxConstraints.expand()));
     }
 
-    if (alignment != null)
+    if (alignment != null) {
       current = Align(alignment: alignment, child: current);
+    }
 
     if (padding != null) {
       current = Padding(padding: padding, child: current);
     }
 
-    if (decoration != null)
+    if (decoration != null) {
       current = DecoratedBox(decoration: decoration, child: current);
+    }
 
     if (foregroundDecoration != null) {
       current = DecoratedBox(
@@ -276,15 +279,17 @@ class Container extends StatelessWidget {
           child: current);
     }
 
-    if (constraints != null)
+    if (constraints != null) {
       current = ConstrainedBox(constraints: constraints, child: current);
+    }
 
     if (margin != null) {
       current = Padding(padding: margin, child: current);
     }
 
-    if (transform != null)
+    if (transform != null) {
       current = Transform(transform: transform, child: current);
+    }
 
     return current;
   }

@@ -144,10 +144,11 @@ class Flex extends MultiChildWidget {
       // Size remaining (flexible) items, find the maximum cross size.
       for (Widget child in children) {
         final int flex = child is Expanded ? child.flex : 0;
-        if (flex > 0)
+        if (flex > 0) {
           maxCrossSize =
               math.max(maxCrossSize, childSize(child, spacePerFlex * flex));
         }
+      }
 
       return maxCrossSize;
     }

@@ -359,8 +359,9 @@ FittedSizes applyBoxFit(BoxFit fit, PdfPoint inputSize, PdfPoint outputSize) {
   if (inputSize.y <= 0.0 ||
       inputSize.x <= 0.0 ||
       outputSize.y <= 0.0 ||
-      outputSize.x <= 0.0)
+      outputSize.x <= 0.0) {
     return const FittedSizes(PdfPoint.zero, PdfPoint.zero);
+  }
 
   PdfPoint sourceSize, destinationSize;
   switch (fit) {
@@ -370,12 +371,13 @@ FittedSizes applyBoxFit(BoxFit fit, PdfPoint inputSize, PdfPoint outputSize) {
       break;
     case BoxFit.contain:
       sourceSize = inputSize;
-      if (outputSize.x / outputSize.y > sourceSize.x / sourceSize.y)
+      if (outputSize.x / outputSize.y > sourceSize.x / sourceSize.y) {
         destinationSize =
             PdfPoint(sourceSize.x * outputSize.y / sourceSize.y, outputSize.y);
-      else
+      } else {
         destinationSize =
             PdfPoint(outputSize.x, sourceSize.y * outputSize.x / sourceSize.x);
+      }
       break;
     case BoxFit.cover:
       if (outputSize.x / outputSize.y > inputSize.x / inputSize.y) {
@@ -408,10 +410,12 @@ FittedSizes applyBoxFit(BoxFit fit, PdfPoint inputSize, PdfPoint outputSize) {
       sourceSize = inputSize;
       destinationSize = inputSize;
       final double aspectRatio = inputSize.x / inputSize.y;
-      if (destinationSize.y > outputSize.y)
+      if (destinationSize.y > outputSize.y) {
         destinationSize = PdfPoint(outputSize.y * aspectRatio, outputSize.y);
-      if (destinationSize.x > outputSize.x)
+      }
+      if (destinationSize.x > outputSize.x) {
         destinationSize = PdfPoint(outputSize.x, outputSize.x / aspectRatio);
+      }
       break;
   }
   return FittedSizes(sourceSize, destinationSize);

@@ -130,18 +130,20 @@ class Stack extends MultiChildWidget {
         final Positioned positioned = child;
         BoxConstraints childConstraints = const BoxConstraints();
 
-        if (positioned.left != null && positioned.right != null)
+        if (positioned.left != null && positioned.right != null) {
           childConstraints = childConstraints.tighten(
               width: box.width - positioned.right - positioned.left);
-        else if (positioned.width != null)
+        } else if (positioned.width != null) {
           childConstraints = childConstraints.tighten(width: positioned.width);
+        }
 
-        if (positioned.top != null && positioned.bottom != null)
+        if (positioned.top != null && positioned.bottom != null) {
           childConstraints = childConstraints.tighten(
               height: box.height - positioned.bottom - positioned.top);
-        else if (positioned.height != null)
+        } else if (positioned.height != null) {
           childConstraints =
               childConstraints.tighten(height: positioned.height);
+        }
 
         positioned.layout(context, childConstraints, parentUsesSize: true);
         assert(positioned.box != null);