Fix: Label Functions and Methods declartions as Ambient (fixes eslint#162)

Ambient functions do not have a body and will cuase rules to throw
an excpetion. We use the types TSAmbientFunctionExpression and
TSAmbientMethoDeclaration.

Author: soda0289

lib/ast-converter.js

@@ -875,7 +875,7 @@ module.exports = function(ast, extra) {
                         return modifier.kind === ts.SyntaxKind.DeclareKeyword;
                     });
                     if (isDeclareFunction) {
-                        functionDeclarationType = "DeclareFunction";
+                        functionDeclarationType = "TSAmbientFunctionDeclaration";
                     }
                 }
 
@@ -1074,6 +1074,7 @@ module.exports = function(ast, extra) {
                 // TODO: double-check that these positions are correct
                 var methodLoc = ast.getLineAndCharacterOfPosition(node.name.end + 1),
                     nodeIsMethod = (node.kind === SyntaxKind.MethodDeclaration),
+                    isAmbient = ts.isInAmbientContext(node),
                     method = {
                         type: "FunctionExpression",
                         id: null,
@@ -1136,6 +1137,10 @@ module.exports = function(ast, extra) {
                             methodDefinitionType = "TSAbstractMethodDefinition";
                         }
                     }
+                    if (isAmbient) {
+                        methodDefinitionType = "TSAmbientMethodDefinition";
+                        method.type = "TSAmbientFunctionExpression";
+                    }
 
                     assign(result, {
                         type: methodDefinitionType,
@@ -1167,6 +1172,7 @@ module.exports = function(ast, extra) {
                 var constructorIsStatic = Boolean(node.flags & ts.NodeFlags.Static),
                     firstConstructorToken = constructorIsStatic ? ts.findNextToken(node.getFirstToken(), ast) : node.getFirstToken(),
                     constructorLoc = ast.getLineAndCharacterOfPosition(node.parameters.pos - 1),
+                    constructorIsAmbient = ts.isInAmbientContext(node),
                     constructor = {
                         type: "FunctionExpression",
                         id: null,
@@ -1230,8 +1236,14 @@ module.exports = function(ast, extra) {
                     };
                 }
 
+                var constructorMethodDefinitionType = "MethodDefinition";
+                if (constructorIsAmbient) {
+                    constructorMethodDefinitionType = "TSAmbientMethodDefinition";
+                    constructor.type = "TSAmbientFunctionExpression";
+                }
+
                 assign(result, {
-                    type: "MethodDefinition",
+                    type: constructorMethodDefinitionType,
                     key: constructorKey,
                     value: constructor,
                     computed: constructorIsComputed,