Added support for custom object formatters

Custom object formatters allow users to customize how an object is
stringified in matcher failure messages. This can already be done by
adding a `jasmineToString` method to the objects in question. But
it's not always desirable or possible to do that, particularly when
objects of a given "type" do not inherit from a specific prototype.
For instance, suppose a web service returns a list of foos that are
deserialized from JSON, e.g.:

   { fooId: 42, /* more properties */ }

The only way to define `jasmineToString` on those is by writing code to
add it to each instance at runtime. But a custom object formatter can
recognize that the object it's looking at is a foo and format it
accordingly:

   jasmine.addCustomObjectFormatter(function(obj) {
      if (typeof obj.fooId !== 'number') {
            return undefined;
        }

        return '[Foo with ID ' + obj.fooId + ']';
    });

Unlike `jasmineToString`, custom object formatters are scoped to a
particular spec or suite and don't require any changes to the code
under test.

spec/core/asymmetric_equality/ArrayContainingSpec.js

@@ -42,9 +42,14 @@ describe("ArrayContaining", function() {
   });
 
   it("jasmineToStrings itself", function() {
-    var containing = new jasmineUnderTest.ArrayContaining([]);
+    var sample = [],
+      matcher = new jasmineUnderTest.ArrayContaining(sample),
+      pp = jasmine.createSpy('pp').and.returnValue('sample');
 
-    expect(containing.jasmineToString()).toMatch("<jasmine.arrayContaining");
+    expect(matcher.jasmineToString(pp)).toEqual(
+      '<jasmine.arrayContaining(sample)>'
+    );
+    expect(pp).toHaveBeenCalledWith(sample);
   });
 
   it("uses custom equality testers", function() {

spec/core/asymmetric_equality/ArrayWithExactContentsSpec.js

@@ -30,9 +30,14 @@ describe("ArrayWithExactContents", function() {
   });
 
   it("jasmineToStrings itself", function() {
-    var matcher = new jasmineUnderTest.ArrayWithExactContents([]);
+    var sample = [],
+      matcher = new jasmineUnderTest.ArrayWithExactContents(sample),
+      pp = jasmine.createSpy('pp').and.returnValue('sample');
 
-    expect(matcher.jasmineToString()).toMatch("<jasmine.arrayWithExactContents");
+    expect(matcher.jasmineToString(pp)).toEqual(
+      '<jasmine.arrayWithExactContents(sample)>'
+    );
+    expect(pp).toHaveBeenCalledWith(sample);
   });
 
   it("uses custom equality testers", function() {

spec/core/asymmetric_equality/MapContainingSpec.js

@@ -184,8 +184,13 @@ describe('MapContaining', function() {
   });
 
   it('defines a `jasmineToString` method', function() {
-    var containing = new jasmineUnderTest.MapContaining(new Map());
+    var sample = new Map(),
+      containing = new jasmineUnderTest.MapContaining(sample),
+      pp = jasmine.createSpy('pp').and.returnValue('sample');
 
-    expect(containing.jasmineToString()).toMatch(/^<jasmine\.mapContaining/);
+    expect(containing.jasmineToString(pp)).toEqual(
+      '<jasmine.mapContaining(sample)>'
+    );
+    expect(pp).toHaveBeenCalledWith(sample);
   });
 });

spec/core/asymmetric_equality/ObjectContainingSpec.js

@@ -37,9 +37,15 @@ describe("ObjectContaining", function() {
   });
 
   it("jasmineToString's itself", function() {
-    var containing = new jasmineUnderTest.ObjectContaining({});
+    var sample = {},
+      matcher = new jasmineUnderTest.ObjectContaining(sample),
+      pp = jasmine.createSpy('pp').and.returnValue('sample');
+
+    expect(matcher.jasmineToString(pp)).toEqual(
+      '<jasmine.objectContaining(sample)>'
+    );
+    expect(pp).toHaveBeenCalledWith(sample);
 
-    expect(containing.jasmineToString()).toMatch("<jasmine.objectContaining");
   });
 
   it("matches recursively", function() {

spec/core/asymmetric_equality/SetContainingSpec.js

@@ -117,8 +117,13 @@ describe('SetContaining', function() {
   });
 
   it('defines a `jasmineToString` method', function() {
-    var containing = new jasmineUnderTest.SetContaining(new Set());
+    var sample = new Set(),
+      containing = new jasmineUnderTest.SetContaining(sample),
+      pp = jasmine.createSpy('pp').and.returnValue('sample');
 
-    expect(containing.jasmineToString()).toMatch(/^<jasmine\.setContaining/);
+    expect(containing.jasmineToString(pp)).toEqual(
+      '<jasmine.setContaining(sample)>'
+    );
+    expect(pp).toHaveBeenCalledWith(sample);
   });
 });