Change the WebCrypto behavior when importing EC private keys without a public key.

content/test/data/webcrypto/ec_private_keys.json

 // This file contains valid EC private keys in both JWK format, and PKCS8 format.
 [
   {
     "curve": "P-256",
     "jwk": {
       "kty": "EC",
       "crv": "P-256",
       "d": "H-M5UMX0YRJK6ZLCvf3xxzsWFfVxvVZ-YNGaofSM30I",
       "x": "fBEMZtz9qAf25p5F3bPHT2mhSE0gPo3Frajpqd18s8c",
       "y": "DfRImG5RveXRV2-ZkB-cLGqAakf9kHZDpyuDVZfvyMY"
@@ skipping 55 matching lines @@
   {
     "curve": "P-256",
     "jwk": {
       "kty":"EC",
       "crv": "P-256",
       "d": "AMdmwJND1DN-6tBaXOFsiZgIyPFcfHpMffcjHITC1bw",
       "x":"t9PMXQhdi3cHs-Vy0iPxbNXid9P7k_sbGxGycoRjzsU",
       "y":"gKEET8d0MXwkffogoA-3jRQZjTSmNxeUfoxxQ-y53xM"
     },
     "pkcs8": "308186020100301306072A8648CE3D020106082A8648CE3D030107046C306A020101041FC766C09343D4337EEAD05A5CE16C899808C8F15C7C7A4C7DF7231C84C2D5BCA14403420004B7D3CC5D085D8B7707B3E572D223F16CD5E277D3FB93FB1B1B11B2728463CEC580A1044FC774317C247DFA20A00FB78D14198D34A63717947E8C7143ECB9DF13"
+  },
+
+  // In this test the PKCS8 input data does NOT contain the optional publicKey field.
+  //  * When importing from PKCS8 and then exporting to JWK, the "x" and "y"
+  //    parameters are synthesized.
+  //  * When importing from PKCS8 and then exporting back to PKCS8, the
+  //    publicKey field is added. The input is "pkcs8_input", and the expected
+  //    exported data is "pkcs8"
+  {
+    "curve": "P-256",
+    "jwk": {
+      "kty": "EC",
+      "crv": "P-256",
+      "d": "H-M5UMX0YRJK6ZLCvf3xxzsWFfVxvVZ-YNGaofSM30I",
+      "x": "fBEMZtz9qAf25p5F3bPHT2mhSE0gPo3Frajpqd18s8c",
+      "y": "DfRImG5RveXRV2-ZkB-cLGqAakf9kHZDpyuDVZfvyMY"
+    },
+    "pkcs8_input": "3041020100301306072A8648CE3D020106082A8648CE3D0301070427302502010104201FE33950C5F461124AE992C2BDFDF1C73B1615F571BD567E60D19AA1F48CDF42",
+    "pkcs8": "308187020100301306072A8648CE3D020106082A8648CE3D030107046D306B02010104201FE33950C5F461124AE992C2BDFDF1C73B1615F571BD567E60D19AA1F48CDF42A144034200047C110C66DCFDA807F6E69E45DDB3C74F69A1484D203E8DC5ADA8E9A9DD7CB3C70DF448986E51BDE5D1576F99901F9C2C6A806A47FD907643A72B835597EFC8C6"

[Ryan Sleevi, 2015/01/02 22:45:23]

I find naming the inputs "pkcs8" and "pkcs8_input" to be confusing. Is there a
better naming you can suggest? expected_pkcs8 ?

[eroman, 2015/01/02 23:49:38]

A couple ideas:

 (1) Rename them to "original_pkcs8" and "exported_pkcs8" for this test case. In
all the other tests a symmetry between the imported and exported data is assumed
and it is simply called "pkcs8"

 (2) Same concept as above, but rather than make this test case special, require
all the other tests to specify separate input/output values. Less excited about
this as it leads to more duplication

 (3) Remove this test data from ec_private_keys and create a separate C++ test
that explores this individually. Less excited about more C++ code though.

 (4) Re-write the whole test so instead of constituting equivalent JWK/PKCS8
pairs (which breaks apart for this case) it instead expresses an input (format,
keydata) and an ouptut (format, keydata). To represent the same set of tests
more pairs will be needed (jwk -> jwk, pkcs8 -> pkcs8, jwk->pkcs8, pkcs8->jwk),
however it will be more readable for this particular instance.

[eroman, 2015/01/06 21:14:36]

Ryan: I have changed to strategy (1). You can see those differences here:
https://codereview.chromium.org/835633002/diff2/20001:40001/content/test/data...

Let me know if this is clearer.

   }
 ]