Analyzer must support cascaded calls in initializer lists

[gbracha]

The grammar has changed.

[bwilkerson]

Added this to the M2 milestone.

[clayberg]

Set owner to @scheglov.

[scheglov]

Removed this from the M2 milestone.
Added this to the M3 milestone.

[scheglov]

Added Accepted label.

[scheglov]

It seems Analyzer already supports this.

class A {
  var f;
  A() : f=""..length;
}

gives no warnings or errors.

Adding specific test for initializers in this CL.
https://codereview.chromium.org/11548016

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Added Started label.

[scheglov]

https://code.google.com/p/dart/source/detail?r=16048

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Removed this from the M3 milestone.
Added this to the M2 milestone.
Added Fixed label.