Implement coroutineContext intrinsic

This intrinsic allows coroutine to access its context without suspention
and, furthermore, disabling tail-call optimization.
KT-17609: Fixed

compiler/backend-common/src/org/jetbrains/kotlin/backend/common/commonCoroutineCodegenUtil.kt

@@ -17,16 +17,19 @@
 package org.jetbrains.kotlin.backend.common
 
 import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.descriptors.PropertyGetterDescriptor
 import org.jetbrains.kotlin.incremental.components.NoLookupLocation
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.DescriptorEquivalenceForOverrides
 import org.jetbrains.kotlin.resolve.DescriptorUtils
+import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameSafe
 import org.jetbrains.kotlin.resolve.descriptorUtil.module
 
 val SUSPEND_COROUTINE_OR_RETURN_NAME = Name.identifier("suspendCoroutineOrReturn")
 val COROUTINE_SUSPENDED_NAME = Name.identifier("COROUTINE_SUSPENDED")
 
 val COROUTINES_INTRINSICS_PACKAGE_FQ_NAME = DescriptorUtils.COROUTINES_PACKAGE_FQ_NAME.child(Name.identifier("intrinsics"))
+val COROUTINE_CONTEXT_FQ_NAME = COROUTINES_INTRINSICS_PACKAGE_FQ_NAME.child(Name.identifier("coroutineContext"))
 
 fun FunctionDescriptor.isBuiltInSuspendCoroutineOrReturn(): Boolean {
     if (name != SUSPEND_COROUTINE_OR_RETURN_NAME) return false
@@ -42,3 +45,7 @@ fun FunctionDescriptor.getBuiltInSuspendCoroutineOrReturn() =
         module.getPackage(COROUTINES_INTRINSICS_PACKAGE_FQ_NAME).memberScope
                 .getContributedFunctions(SUSPEND_COROUTINE_OR_RETURN_NAME, NoLookupLocation.FROM_BACKEND)
                 .singleOrNull()
+
+fun FunctionDescriptor.isBuiltInCoroutineContext() =
+        (this as? PropertyGetterDescriptor)?.correspondingProperty?.fqNameSafe == COROUTINE_CONTEXT_FQ_NAME
+