IR: push down implementations of startOffset/endOffset/type/...

Do not store these as properties in IrElementBase, IrExpressionBase and
similar classes. This helps to reduce boilerplate in implementations
(just "override val" in the constructor, instead of taking a parameter
and passing it to the superclass), and also slightly optimizes memory in
cases where the value is trivial (UNDEFINED_OFFSET, 0, etc) and thus
does not need to be stored.

compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/expressions/impl/IrBlockBodyImpl.kt

@@ -22,7 +22,10 @@ import org.jetbrains.kotlin.ir.declarations.IrFactory
 import org.jetbrains.kotlin.ir.declarations.impl.IrFactoryImpl
 import org.jetbrains.kotlin.ir.expressions.IrBlockBody
 
-class IrBlockBodyImpl(startOffset: Int, endOffset: Int) : IrElementBase(startOffset, endOffset), IrBlockBody {
+class IrBlockBodyImpl(
+    override val startOffset: Int,
+    override val endOffset: Int
+) : IrElementBase(), IrBlockBody {
     constructor(startOffset: Int, endOffset: Int, statements: List<IrStatement>) : this(startOffset, endOffset) {
         this.statements.addAll(statements)
     }

compiler/ir/ir.tree.impl/src/org/jetbrains/kotlin/ir/expressions/impl/IrExpressionBodyImpl.kt

@@ -23,10 +23,10 @@ import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.IrExpressionBody
 
 class IrExpressionBodyImpl(
-    startOffset: Int,
-    endOffset: Int,
+    override val startOffset: Int,
+    override val endOffset: Int,
     initializer: (IrExpressionBody.() -> Unit)? = null
-) : IrElementBase(startOffset, endOffset), IrExpressionBody {
+) : IrElementBase(), IrExpressionBody {
     init {
         initializer?.invoke(this)
     }