Verify that callers correctly set parentUsesSize if they use the child's size (and fix a few cases …

sky/sdk/lib/framework/rendering/paragraph.dart

Index: sky/sdk/lib/framework/rendering/paragraph.dart
diff --git a/sky/sdk/lib/framework/rendering/paragraph.dart b/sky/sdk/lib/framework/rendering/paragraph.dart
index 16caee3a9d99b5ef995d21a043bd51961bdbe8e1..3643ebb2120e194cdb202cf24cb00f7a8ee527c8 100644
--- a/sky/sdk/lib/framework/rendering/paragraph.dart
+++ b/sky/sdk/lib/framework/rendering/paragraph.dart
@@ -211,5 +211,11 @@ class RenderParagraph extends RenderBox {
 
   // we should probably expose a way to do precise (inter-glpyh) hit testing
 
-  String debugDescribeSettings(String prefix) => '${super.debugDescribeSettings(prefix)}${prefix}style:\n${style.toString("$prefix  ")}\n${prefix}text: ${text}\n';
+  String debugDescribeSettings(String prefix) {
+    String result = '${super.debugDescribeSettings(prefix)}';
+    if (style != null)
+      result += '${prefix}style:\n' + style.toString('$prefix  ') + '\n';
+    result += '${prefix}text: ${text}\n';
+    return result;
+  }
 }