Roll Observatory packages and add a roll script

packages/dart_style/test/splitting/invocations.stmt

+40 columns                              |
+>>> split all chained calls if they don't fit on one line
+compiler.something().something().something();
+<<<
+compiler
+    .something()
+    .something()
+    .something();
+>>> do not split chained calls if not needed
+compiler.something().something().some();
+<<<
+compiler.something().something().some();
+>>> don't split before implicit receiver
+return
+     call({'type': type, 'id': id})
+    .then(deserializeAsset);
+<<<
+return call({'type': type, 'id': id})
+    .then(deserializeAsset);
+>>> allows chained calls on one line with multi-line last argument list
+compiler
+    .run(script)
+    .then((_) {
+  body;
+});
+<<<
+compiler.run(script).then((_) {
+  body;
+});
+>>> allow inline chains before and after a hard newline
+compiler.a().b((_) {
+  body;
+}).c().d();
+<<<
+compiler.a().b((_) {
+  body;
+}).c().d();
+>>> allow an inline chain before a hard newline but not after
+compiler.a().b((_) {
+  body;
+}).somethingLong().somethingLong().somethingLong();
+<<<
+compiler.a().b((_) {
+  body;
+})
+    .somethingLong()
+    .somethingLong()
+    .somethingLong();
+>>> allow an inline chain after a hard newline but not before
+compiler.somethingLong().somethingLong().somethingLong((_) {
+  body;
+}).a().b();
+<<<
+compiler
+    .somethingLong()
+    .somethingLong()
+    .somethingLong((_) {
+  body;
+}).a().b();
+>>> nest calls one more than target
+someVeryLongExpression = someVeryLongExpression.someLongMethod();
+<<<
+someVeryLongExpression =
+    someVeryLongExpression
+        .someLongMethod();
+>>> split properties after a method chain
+compiler.method().method().method().property.property;
+<<<
+compiler
+    .method()
+    .method()
+    .method()
+    .property
+    .property;
+>>> split properties in a method chain
+compiler.method().property.method().property.method();
+<<<
+compiler
+    .method()
+    .property
+    .method()
+    .property
+    .method();
+>>> do not split leading properties in a chain
+compiler.property.property.method().method().method();
+<<<
+compiler.property.property
+    .method()
+    .method()
+    .method();
+>>> do not split leading properties even if others splits
+compiler.property.method().property.method();
+<<<
+compiler.property
+    .method()
+    .property
+    .method();
+>>> split between a pair of properties
+avian.bovine.canine.equine.feline.piscine.orycteropodian.camelid;
+<<<
+avian.bovine.canine.equine.feline
+    .piscine.orycteropodian.camelid;
+>>> split before all properties if they don't fit on two lines
+avian.bovine.canine.equine.feline.piscine.orycteropodian.camelid
+.rangiferine;
+<<<
+avian
+    .bovine
+    .canine
+    .equine
+    .feline
+    .piscine
+    .orycteropodian
+    .camelid
+    .rangiferine;
+>>> unsplit cascade unsplit method
+object.method().method()..c()..c();
+<<<
+object.method().method()..c()..c();
+>>> split cascade unsplit method
+object.method().method()..cascade()..cascade();
+<<<
+object.method().method()
+  ..cascade()
+  ..cascade();
+>>> unsplit cascade split method
+object.method().method().method().method()..cascade()..cascade();
+<<<
+object
+    .method()
+    .method()
+    .method()
+    .method()..cascade()..cascade();
+>>> split cascade split method
+object.method().method().method().method()..cascade()..cascade()..cascade();
+<<<
+object
+    .method()
+    .method()
+    .method()
+    .method()
+      ..cascade()
+      ..cascade()
+      ..cascade();
+>>> cascade setters on method chain
+object.method().method().method().method()..x=1..y=2;
+<<<
+object
+    .method()
+    .method()
+    .method()
+    .method()
+      ..x = 1
+      ..y = 2;
+>>> conditional invocation
+object?.method().method()?.method().method();
+<<<
+object
+    ?.method()
+    .method()
+    ?.method()
+    .method();