JS: add inspection for the case when something with dynamic type implicitly casted to kotlin another type

idea/src/META-INF/plugin.xml

@@ -1553,6 +1553,14 @@
                      language="kotlin"
     />
 
+    <localInspection implementationClass="org.jetbrains.kotlin.idea.inspections.UnsafeCastFromDynamicInspection"
+                     displayName="Implicit (unsafe) cast from dynamic type"
+                     groupName="Kotlin"
+                     enabledByDefault="true"
+                     level="INFO"
+                     language="kotlin"
+    />
+
     <localInspection implementationClass="org.jetbrains.kotlin.idea.inspections.OverridingDeprecatedMemberInspection"
                      shortName="OverridingDeprecatedMember"
                      displayName="Overriding deprecated member"

idea/src/org/jetbrains/kotlin/idea/inspections/UnsafeCastFromDynamicInspection.kt

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2010-2016 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.kotlin.idea.inspections
+
+import com.intellij.codeInspection.LocalInspectionToolSession
+import com.intellij.codeInspection.ProblemsHolder
+import com.intellij.psi.PsiElementVisitor
+import org.jetbrains.kotlin.idea.caches.resolve.analyze
+import org.jetbrains.kotlin.psi.KtExpression
+import org.jetbrains.kotlin.psi.KtVisitorVoid
+import org.jetbrains.kotlin.resolve.BindingContext
+import org.jetbrains.kotlin.resolve.calls.callUtil.getType
+import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
+import org.jetbrains.kotlin.types.TypeUtils
+import org.jetbrains.kotlin.types.isDynamic
+
+class UnsafeCastFromDynamicInspection : AbstractKotlinInspection() {
+    override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean, session: LocalInspectionToolSession): PsiElementVisitor {
+        return object : KtVisitorVoid() {
+            override fun visitExpression(expression: KtExpression) {
+                super.visitExpression(expression)
+
+                val context = expression.analyze(BodyResolveMode.PARTIAL)
+                val expectedType = context[BindingContext.EXPECTED_EXPRESSION_TYPE, expression] ?: return
+                val actualType = expression.getType(context) ?: return
+
+                if (actualType.isDynamic() && !expectedType.isDynamic() && !TypeUtils.noExpectedType(expectedType)) {
+                    holder.registerProblem(expression, "Implicit (unsafe) cast from dynamic to $expectedType")
+                }
+            }
+        }
+    }
+}