Replace resolveToDescriptor with unsafeResolveToDescriptor

Now unsafeResolveToDescriptor is equivalent to resolveToDescriptorIfAny
but throws exception in case no descriptor is found.
Old version of resolveToDescriptor is kept intact but made deprecated.
Some clarifying comments were added

idea/idea-core/src/org/jetbrains/kotlin/idea/core/KotlinIndicesHelper.kt

@@ -237,7 +237,7 @@ class KotlinIndicesHelper(
     fun getKotlinEnumsByName(name: String): Collection<DeclarationDescriptor> {
         return KotlinClassShortNameIndex.getInstance()[name, project, scope]
                 .filter { it is KtEnumEntry && it in scope }
-                .mapNotNull { it.resolveToDescriptor() }
+                .mapNotNull { it.unsafeResolveToDescriptor() }
                 .filter(descriptorFilter)
                 .toSet()
     }

idea/idea-core/src/org/jetbrains/kotlin/idea/core/KotlinNameSuggestionProvider.kt

@@ -28,7 +28,7 @@ import org.jetbrains.kotlin.asJava.toLightElements
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.descriptors.CallableDescriptor
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
-import org.jetbrains.kotlin.idea.caches.resolve.resolveToDescriptor
+import org.jetbrains.kotlin.idea.caches.resolve.unsafeResolveToDescriptor
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.resolve.calls.callUtil.getResolvedCall
 import org.jetbrains.kotlin.resolve.calls.model.ArgumentMatch
@@ -54,7 +54,7 @@ class KotlinNameSuggestionProvider : NameSuggestionProvider {
                     this += KotlinNameSuggester.getCamelNames(name!!, validator, name.first().isLowerCase())
                 }
 
-                val callableDescriptor = element.resolveToDescriptor(BodyResolveMode.PARTIAL) as CallableDescriptor
+                val callableDescriptor = element.unsafeResolveToDescriptor(BodyResolveMode.PARTIAL) as CallableDescriptor
                 val type = callableDescriptor.returnType
                 if (type != null && !type.isUnit() && !KotlinBuiltIns.isPrimitiveType(type)) {
                     this += KotlinNameSuggester.suggestNamesByType(type, validator)

idea/idea-core/src/org/jetbrains/kotlin/idea/core/Utils.kt

@@ -21,7 +21,7 @@ import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.idea.analysis.computeTypeInContext
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
 import org.jetbrains.kotlin.idea.caches.resolve.getResolutionFacade
-import org.jetbrains.kotlin.idea.caches.resolve.resolveToDescriptor
+import org.jetbrains.kotlin.idea.caches.resolve.unsafeResolveToDescriptor
 import org.jetbrains.kotlin.idea.references.mainReference
 import org.jetbrains.kotlin.idea.resolve.ResolutionFacade
 import org.jetbrains.kotlin.idea.resolve.frontendService
@@ -34,7 +34,6 @@ import org.jetbrains.kotlin.psi.psiUtil.getQualifiedElementSelector
 import org.jetbrains.kotlin.psi.psiUtil.getQualifiedExpressionForSelectorOrThis
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.DelegatingBindingTrace
-import org.jetbrains.kotlin.resolve.bindingContextUtil.getDataFlowInfoAfter
 import org.jetbrains.kotlin.resolve.bindingContextUtil.getDataFlowInfoBefore
 import org.jetbrains.kotlin.resolve.calls.CallResolver
 import org.jetbrains.kotlin.resolve.calls.context.BasicCallResolutionContext
@@ -155,7 +154,7 @@ private fun expectedType(call: Call, bindingContext: BindingContext): KotlinType
 }
 
 fun KtCallableDeclaration.canOmitDeclaredType(initializerOrBodyExpression: KtExpression, canChangeTypeToSubtype: Boolean): Boolean {
-    val declaredType = (resolveToDescriptor() as? CallableDescriptor)?.returnType ?: return false
+    val declaredType = (unsafeResolveToDescriptor() as? CallableDescriptor)?.returnType ?: return false
     val bindingContext = initializerOrBodyExpression.analyze()
     val scope = initializerOrBodyExpression.getResolutionScope(bindingContext, initializerOrBodyExpression.getResolutionFacade())
     val expressionType = initializerOrBodyExpression.computeTypeInContext(scope) ?: return false