[JS IR] Cache JsLocation objects and js function signatures

Memory consumption optimization

js/js.ast/src/org/jetbrains/kotlin/js/backend/ast/JsLocation.kt

@@ -19,12 +19,14 @@ package org.jetbrains.kotlin.js.backend.ast
 import java.io.Reader
 
 data class JsLocation(
-        override val file: String,
-        override val startLine: Int,
-        override val startChar: Int
+    override val file: String,
+    override val startLine: Int,
+    override val startChar: Int
 ) : JsLocationWithSource {
-    override val identityObject: Any? = null
-    override val sourceProvider: () -> Reader? = { null }
+    override val identityObject: Any?
+        get() = null
+    override val sourceProvider: () -> Reader?
+        get() = { null }
 
     override fun asSimpleLocation(): JsLocation = this
 }
@@ -40,7 +42,7 @@ interface JsLocationWithSource {
 }
 
 class JsLocationWithEmbeddedSource(
-        private val location: JsLocation,
-        override val identityObject: Any?,
-        override val sourceProvider: () -> Reader?
-) : JsLocationWithSource by location
+    private val location: JsLocation,
+    override val identityObject: Any?,
+    override val sourceProvider: () -> Reader?
+) : JsLocationWithSource by location