Make CharSequence.length a function instead of property

And String.length as well.

This is done for JVM interoperability: java.lang.CharSequence is an open class
and has a function 'length()' which should be implemented in subclasses
somehow.

A minor unexpected effect of this is that String.length() is now a compile-time
constant (it wasn't such as a property because properties are not supported in
compile-time constant evaluation)

 #KT-3571 Fixed

compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/IntrinsicMethods.java

@@ -130,9 +130,6 @@ public class IntrinsicMethods {
             declareIntrinsicFunction(typeName + "Iterator", "next", 0, ITERATOR_NEXT);
         }
 
-        declareIntrinsicProperty("CharSequence", "length", new StringLength());
-        declareIntrinsicProperty("String", "length", new StringLength());
-
         declareArrayMethods();
     }
 
@@ -168,10 +165,6 @@ public class IntrinsicMethods {
         }
     }
 
-    private void declareIntrinsicProperty(@NotNull String className, @NotNull String methodName, @NotNull IntrinsicMethod implementation) {
-        declareIntrinsicFunction(className, methodName, -1, implementation);
-    }
-
     private void declareIntrinsicFunction(
             @NotNull String className,
             @NotNull String methodName,

compiler/backend/src/org/jetbrains/jet/codegen/intrinsics/StringLength.kt

@@ -1,38 +0,0 @@
-/*
- * Copyright 2010-2014 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.jetbrains.jet.codegen.intrinsics
-
-import com.intellij.psi.PsiElement
-import org.jetbrains.org.objectweb.asm.Type
-import org.jetbrains.jet.codegen.ExpressionCodegen
-import org.jetbrains.jet.codegen.StackValue
-import org.jetbrains.jet.lang.psi.JetExpression
-
-public class StringLength : LazyIntrinsicMethod() {
-    override fun generateImpl(
-            codegen: ExpressionCodegen,
-            returnType: Type,
-            element: PsiElement?,
-            arguments: List<JetExpression>,
-            receiver: StackValue
-    ): StackValue {
-        return StackValue.operation(Type.INT_TYPE) {
-            receiver.put(receiver.type, it)
-            it.invokeinterface("java/lang/CharSequence", "length", "()I")
-        }
-    }
-}