Support getOccurrencesAtPosition for 'throw' keywords.

Also revised behavior for 'return' keywords in that when the position
resides on a 'return' statement, 'throw' keywords in the same
function scope that are not within a try-block are also highlighted.

src/services/services.ts

@@ -2378,6 +2378,11 @@ module ts {
                         return getReturnOccurrences(<ReturnStatement>node.parent);
                     }
                     break;
+                case SyntaxKind.ThrowKeyword:
+                    if (hasKind(node.parent, SyntaxKind.ThrowStatement)) {
+                        return getThrowOccurrences(<ThrowStatement>node.parent);
+                    }
+                    break;
                 case SyntaxKind.TryKeyword:
                 case SyntaxKind.CatchKeyword:
                 case SyntaxKind.FinallyKeyword:
@@ -2491,12 +2496,97 @@ module ts {
                 }
 
                 var keywords: Node[] = []
-                forEachReturnStatement(<Block>(<FunctionDeclaration>func).body, returnStatement => {
+                forEachReturnStatement(<Block>func.body, returnStatement => {
                     pushKeywordIf(keywords, returnStatement.getFirstToken(), SyntaxKind.ReturnKeyword);
                 });
 
+                // Include 'throw' statements that do not occur within a try block.
+                forEach(aggregateOwnedThrowStatements(func.body), throwStatement => {
+                    pushKeywordIf(keywords, throwStatement.getFirstToken(), SyntaxKind.ThrowKeyword);
+                });
+
                 return map(keywords, getReferenceEntryFromNode);
             }
+            
+            function getThrowOccurrences(throwStatement: ThrowStatement) {
+                var owner = getContextualThrowStatementOwner(throwStatement);
+
+                if (!owner) {
+                    return undefined;
+                }
+
+                var keywords: Node[] = [];
+                
+                forEach(aggregateOwnedThrowStatements(owner), throwStatement => {
+                    pushKeywordIf(keywords, throwStatement.getFirstToken(), SyntaxKind.ThrowKeyword);
+                });
+
+                // If the "owner" is a function, then we equate 'return' and 'throw' statements in their
+                // ability to "jump out" of the function, and include occurrences for both.
+                if (owner.kind === SyntaxKind.FunctionBlock) {
+                    forEachReturnStatement(<Block>owner, returnStatement => {
+                        pushKeywordIf(keywords, returnStatement.getFirstToken(), SyntaxKind.ReturnKeyword);
+                    });
+                }
+                
+                return map(keywords, getReferenceEntryFromNode);
+            }
+
+            /**
+             * Aggregates all throw-statements within this node *without* crossing
+             * into function boundaries and try-blocks.
+             */
+            function aggregateOwnedThrowStatements(node: Node): ThrowStatement[] {
+                var statementAccumulator: ThrowStatement[] = []
+                aggregate(node);
+                return statementAccumulator;
+
+                function aggregate(node: Node): void {
+                    if (node.kind === SyntaxKind.ThrowStatement) {
+                        statementAccumulator.push(<ThrowStatement>node);
+                    }
+                    else if (node.kind === SyntaxKind.TryStatement) {
+                        var tryStatement = <TryStatement>node;
+                        
+                        if (tryStatement.catchBlock) {
+                            aggregate(tryStatement.catchBlock);
+                        }
+                        if (tryStatement.finallyBlock) {
+                            aggregate(tryStatement.finallyBlock);
+                        }
+                    }
+                    // Do not cross function boundaries.
+                    else if (!isAnyFunction(node)) {
+                        forEachChild(node, aggregate);
+                    }
+                };
+            }
+
+            /**
+             * For lack of a better name, this function takes a throw statement and returns the first
+             * encountered ancestor that is a try-block, function-block, or source file.
+             */
+            function getContextualThrowStatementOwner(throwStatement: ThrowStatement): Node {
+                var child: Node = throwStatement;
+
+                while (child.parent) {
+                    var parent = child.parent;
+
+                    if (parent.kind === SyntaxKind.FunctionBlock || parent.kind === SyntaxKind.SourceFile) {
+                        return parent;
+                    }
+                    
+                    // A throw-statement is only owned by a try-statement if it occurs in the try block.
+                    // Otherwise, it is owned by the next closest function-block or try-block.
+                    if (parent.kind === SyntaxKind.TryStatement && child === (<TryStatement>parent).tryBlock) {
+                        return child;
+                    }
+
+                    child = parent;
+                }
+
+                return undefined;
+            }
 
             function getTryCatchFinallyOccurrences(tryStatement: TryStatement): ReferenceEntry[] {
                 var keywords: Node[] = [];