[SPARK-6428][SQL] Removed unnecessary typecasts in MutableInt, MutableDouble etc.

marmbrus rxin I believe these typecasts are not required in the presence of explicit return types.

Author: Alexander Slesarenko <avslesarenko@gmail.com>

Closes #9262 from aslesarenko/remove-typecasts.

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/SpecificMutableRow.scala

@@ -41,7 +41,7 @@ import org.apache.spark.unsafe.types.UTF8String
  *     val newCopy = new Mutable$tpe
  *     newCopy.isNull = isNull
  *     newCopy.value = value
- *     newCopy.asInstanceOf[this.type]
+ *     newCopy
  *   }
  * }"""
  * }.foreach(println)
@@ -78,7 +78,7 @@ final class MutableInt extends MutableValue {
     val newCopy = new MutableInt
     newCopy.isNull = isNull
     newCopy.value = value
-    newCopy.asInstanceOf[MutableInt]
+    newCopy
   }
 }
 
@@ -93,7 +93,7 @@ final class MutableFloat extends MutableValue {
     val newCopy = new MutableFloat
     newCopy.isNull = isNull
     newCopy.value = value
-    newCopy.asInstanceOf[MutableFloat]
+    newCopy
   }
 }
 
@@ -108,7 +108,7 @@ final class MutableBoolean extends MutableValue {
     val newCopy = new MutableBoolean
     newCopy.isNull = isNull
     newCopy.value = value
-    newCopy.asInstanceOf[MutableBoolean]
+    newCopy
   }
 }
 
@@ -123,7 +123,7 @@ final class MutableDouble extends MutableValue {
     val newCopy = new MutableDouble
     newCopy.isNull = isNull
     newCopy.value = value
-    newCopy.asInstanceOf[MutableDouble]
+    newCopy
   }
 }
 
@@ -138,7 +138,7 @@ final class MutableShort extends MutableValue {
     val newCopy = new MutableShort
     newCopy.isNull = isNull
     newCopy.value = value
-    newCopy.asInstanceOf[MutableShort]
+    newCopy
   }
 }
 
@@ -153,7 +153,7 @@ final class MutableLong extends MutableValue {
     val newCopy = new MutableLong
     newCopy.isNull = isNull
     newCopy.value = value
-    newCopy.asInstanceOf[MutableLong]
+    newCopy
   }
 }
 
@@ -168,7 +168,7 @@ final class MutableByte extends MutableValue {
     val newCopy = new MutableByte
     newCopy.isNull = isNull
     newCopy.value = value
-    newCopy.asInstanceOf[MutableByte]
+    newCopy
   }
 }
 
@@ -183,7 +183,7 @@ final class MutableAny extends MutableValue {
     val newCopy = new MutableAny
     newCopy.isNull = isNull
     newCopy.value = value
-    newCopy.asInstanceOf[MutableAny]
+    newCopy
   }
 }